Seymour said individuals and families who were suffering should take precedence over sporting and cultural event group bookings.
The Government halted MIQ room availability on Tuesday and postponed the next room release, but said this freeze was temporary.
Seymour said even before this week's freeze, people with a need to return home had been locked out of the lottery.
The Border Exception Ministerial Group decides group allocations in blocks of a few months at a time.
"The Wellington establishment has insulated itself from the effects of its decisions," Seymour said.
He said the Government might need to have difficult discussions this year with some groups already promised places.
"I wouldn't put any of these sporting or business opportunities ahead of the heartbreaking cases I hear every day of the people with real human costs, who in some cases never met their kid because it's so hard to get into New Zealand."
Covid-19 Response Minister Chris Hipkins said international expos were important to let Kiwi businesses showcase innovative products and develop new export markets.
"Former National Government Economic Development Minister Simon Bridges set aside tens of millions of dollars in 2017 to be part of the Dubai Expo," Hipkins said.
"This Government supports opportunities to boost international trade, and not allocating spaces in MIQ for attendees would be a huge waste of the earlier investment."
He told the Herald: "We do, however, totally acknowledge the frustrations of families who have been unable to secure a room in MIQ. Allocating rooms is a very difficult balancing act."
Hipkins also mentioned the group booking allocations at the Labour caucus retreat in Taranaki.
"We've had a good look at the group bookings to see if we can trim anything more back from those."
He said he had not yet seen a full report on possible changes or cuts.
Other MIQ group allocations approved this year included a booking for 181 people connected with the Women's Cricket World Cup.
There is also a health worker allocation of 300 rooms per month and the US, Korean and European Antarctic Programmes have 281 people approved for this year.
Not all sporting groups have been successful - applications for almost 500 places related to sports events have been declined since last February.