There seem to be quite a few people that consider Dr. Gebru to be one of the leading scientists within that specific (sub)field.
I don't know the field well enough to have an opinion on the merits but it seems like a view one might disagree with but would not be surprised to find somebody to hold.
But calling someone "one of the world's leading scientists within their specific subfield" is a much, much weaker claim than calling them "one of the world's leading scientists". People in the latter category win Nobel Prizes, not Twitter fights.
When both people involved share a subfield and the piece is talking about what's fundamentally intra-subfield drama, I'd say there are three possibilities:
1) They meant "within the subfield" but assumed it could be taken from context
2) They meant "within the subfield" but have an overinflated notion of the importance of their subfield
3) They genuinely believe the strongest form of the claim
Which of these possibilities one considers most likely probably depends more on one's prior opinion of the people involved than anything else, and I continue to not really have a prior opinion because this whole situation is a trainwreck and I don't know the background well enough to be able to even start to try and read past the biases of the various people commenting.
I don't know the field well enough to have an opinion on the merits but it seems like a view one might disagree with but would not be surprised to find somebody to hold.