Not really. That has to be a bug in kbin, not a problem with Lemmy. Lemmy allows admins to delete stuff off their own instance, but kbin shouldn't be just accepting that as a mod action from any admin on any server it's federated with. That doesn't even make sense. I assume it's just a weird interaction of different ways of handling things on kbin and Lemmy.
To be fair, they said the reason they were defederating from those two instances in particular is because most of their moderation involved people from them. They didn't expand beehaw beyond what they could handle, the rest of lemmy expanded beyond what they could handle. If this really is just a temporary measure, which is also what they said, then I think it's pretty reasonable.