I also disagree that it’s especially political. It’s a small name change to be more considerate. The only reason this is “political” — and “merge requests” wouldn’t be — is that for some reason a small group of people are very loudly offended by it.
It's hardly surprising the priesthood of developers rally against any changes to their sacrosankt nonsensical namings. Merge is different from pull/push though.
Pull is literally an alias for fetch followed by merge. GitLab already calls them merge requests, which caused approximately zero drama, so we have empirical evidence that no one actually cares about these things when they can’t pretend to be offended by them.