But English management backed Shield's decision to chase his test rugby dreams, highlighting that they had not done anything illegal.
"We're just abiding by World Rugby laws," England defence coach Paul Gustard told Sky Sports.
"He's eligible to play for England and we're delighted to have a quality player like him available."
"Sometimes this happens ... you know, Martin Johnson played for New Zealand Colts,"
"But the main thing is we are not doing anything that's illegal, so we are looking forward to having him in the squad."
Shields qualifies for England through his parents, both of whom emigrated to New Zealand in their childhood, but Pichot went further by suggesting that parentage should not be considered sufficient criteria to play for a country where you have not lived.
Responding to the suggestion by Stuart Barnes, the former England fly-half, that Shields' selection was not dissimilar to Pacific Island players representing the All Blacks, Pichot said: "Two things wrong don't make 1 right. Still think (regulations can say another thing) it depends in each case and how many years you have lived and love the country and jersey you are representing. [How] can we measure that? By parents? Grand parents? Years? Very difficult. I have my personal opinion."
Pichot's comments are likely to cause embarrassment to the RFU, with the governing body already under fire for selecting Shields before he joins Wasps next season. England eligibility rules state that Jones can only select players based in England but Shields is yet to play a game in the Premiership.
Shields also represented New Zealand Under-20s when they defeated England to win the World Championship in 2011, playing against six of his new team-mates on this tour in George Ford, Owen Farrell, Elliot Daly, Mako Vunipola, Joe Launchbury and Dan Robson.
Steve Hansen, the All Blacks head coach, said last month that Shields - who took part in his first training session with the England squad in Durban on Tuesday, having arrived from New Zealand on Sunday - would probably have been selected for New Zealand this year if he had not chosen to pledge his international future to England.
It is not the first time Pichot, who was one of the key campaigners for World Rugby's decision last year to extend the qualifying period from three to five years, has spoken out about the increasing trend for players to represent
"When you have players who haven't lived in the country that they represent, it's not great," said Pichot, when he was appointed as World Rugby vice-chairman in 2016. "I think it is very important to keep the identity of our national teams. As a cultural thing, as an inspiration to new kids, I think having on your team players who have not lived [for long] in the country they are [representing] I think it's not right.
"When I see the national anthem and people not singing it, it confuses me a little bit."
Chris Robshaw, who now faces competition from Shields for a place in the England back row during the three-Test series against the Springboks, insisted he has no issue with Shields' nationality or the fact that the he has not yet played for an English club.
"We are getting to know him a bit," said Robshaw. "Due to the jet lag (protocol) he trained for the first time on Tuesday. He is a good lad - hungry and seems like a good lad to have around.
"It is always exciting when new guys come into camp because they bring in new ideas, they might do a breakdown drill completely different to anything you have seen before. That is why it is great to work with different coaches and players because you get a more rounded game.
"There is competition in all places. I think that is where we are as a squad. Of course you want to be in that starting XV but you want to help each other get better and if we help each other get better then we will be a better squad."
Neal Hatley, England's scrum coach, said: "We all know where he (Shields) is from so he just spoke about looking forward to getting stuck in really. He's a man of few words and the players respect that."
Meanwhile, England are facing a fresh injury concern ahead of the first Test against South Africa in Johannesburg on Saturday, with Launchbury a serious doubt after missing Tuesday's squad training session in Durban with a calf injury.
Launchbury, who is expected to be named in the starting XV alongside Maro Itoje in the second row to face the Springboks if fit, took part in stretching exercises on his own at the training pitch beside the Kings Stadium in Durban.
It is understood he sustained the injury during a training session at Pennyhill Park last Friday.
"If he is not fit to play 80 minutes then we'd expect Nick Isiekwe or Jonny Hill to step up and fill those shoes," Hatley added. "Launchers has played over 50 Tests now so he has valuable experience, but if he's not fit to go then it's a great opportunity for those other two boys."
