"It is something they should have thought about more carefully than they did. I can see the superficial appeal, and the clear publicity boost that they are getting," Mallard, MP for Hutt South, told the Herald.
"But I think there are times when they just need to consider the morality of the situation, as opposed to the commerciality of the situation. And, in my view, in this case they have made a big mistake."
Mallard spent six years on the board of the World Anti Doping Agency (Wada), and said during that time the organisation was hampered in its job because of the "inordinate" amount of work related to Armstrong.
"And that was hampered by what were effectively massive legal threats, including against individuals who were executives and board members.
"He caused a focussing on him, when he was clearly cheating and lying about it, and we all knew he was - because the evidence given to us in secret was all there - what he did was he caused a focus on that, which stopped the organisation from doing much other work that was important."
Mallard suggested Armstrong's cheating and the distraction it caused had contributed to others cheating, including the Russians.
"It is very hard to draw the direct line to say that his activities emboldened the Russians. But what we do know is that Wada wasn't as broadly focussed as it should have been, because of the work it was doing on Armstrong."
Mallard said he wasn't a "massive" beer drinker, and preferred craft beers produced by Baylands Brewery or Sprig & Fern.
"But if I am getting beers because I know there's a mixed group of people coming around, Steinlager has been my beer of choice. And it won't be anymore."
Armstrong was stripped of seven Tour de France cycling titles and received a life ban after confessing to benefiting from a sophisticated covert doping programme.
In an email sent to Lion staff - and seen by the Herald - the brewery said Armstrong was in New Zealand for a film shoot.
"We are using Lance to tell a cautionary tale called 'The Consequence', which depicts how much you stand to lose when you pursue success at all costs."
Mallard wasn't convinced by that reasoning.
"It is very hard to pitch a cautionary tale and treat someone as a hero at the same time. They are now still treating him as a hero. And he's not. He's a liar, a cheat and a blackmailer."
