Modern humans are much better at successful bio-insulation. New Zealand's first colonists couldn't help but bring rats, there were rats everywhere there were humans, they snuck about large boats, the colonists were humans, they brought rats and, (with some small but growing exceptions) there are still rats everywhere humans live on New Zealand today.
However, by the time Amundsen Scott was built in 1956 we'd got much more conscious of why this is a bad idea and of how to prevent it. So the only reason there would be ants at Amundsen Scott would be if we intentionally wanted ants there, and I can't think of any reason why we would. If they "escaped" they can't live on Antarctica, the penguins make it look easy but it's really hard to live there, an ant colony would need human intervention to basically feed and protect the ants.
However, by the time Amundsen Scott was built in 1956 we'd got much more conscious of why this is a bad idea and of how to prevent it. So the only reason there would be ants at Amundsen Scott would be if we intentionally wanted ants there, and I can't think of any reason why we would. If they "escaped" they can't live on Antarctica, the penguins make it look easy but it's really hard to live there, an ant colony would need human intervention to basically feed and protect the ants.