I don't see this onboarding risk as being higher with oasis devs than with anyone else, really.
Oasis is and stays a FLOSS app, so they don't get to "control" that in any meaningful sense, especially since the plan is not to transfer ownership of the repository or anything, just have them make some PRs.
And apart from that, they have profiles like anyone else, and with SSB being what it is, being oasis devs also gives them zero extra control.
So the risk of this, in my mind, is exactly the same as on-boarding anyone onto SSB, plus the risk of working with any new person. Frankly I'm not super bothered by the follow-bot thing (and find the wording overly dramatic) but yes, bringing people into the community is always a risk. That dev mostly hurt themselves though by getting the feed blocked a bunch. Sure, they might have benefitted from "soaking" more in the community before.
In any case, if we want to pay non-newcomer community members to do this work, we need to find people qualified and willing to do the work (at that price). And indeed that's what @Powersource tried first, with no result.
I don't think it is reasonable or realistic to expect hired devs to first "join the church of scuttlebutt" and rise through the ranks. Not if we're not willing to also pay for that time...