I always read that more metaphorically - just as his Legion identity has sublated his Twisted Hairs identity, Dry Wells being the site of the destruction of his people and identity has superseded its status as the birthplace of his people and himself. But yeah, you could read into it either way.
But in any case, you do make a good point that if the Twisted Hairs allied themselves early on, they must be jumping on the bandwagon pretty soon. Maybe an outcome of taking Bloomfield for the Legion is that when the players return to Magnum Chasma, there's a party of Twisted Hair scouts approaching Caesar for an alliance since the Legion is now on the margins of their territory and they're aware of them more consciously. If you opt for the canonical outcome of the Rangers at Bloomfield, the only way the Twisted Hairs approach Caesar/the party is if the party completes every other Legion questline including the 'hidden' Flagstaff hooks, since that would elevate the Legion's profile sufficiently to make them interested even if the Legion isn't at the margins of Twisted Hairs territory.