I don't think anyone can answer that. There are posts on here of colonies surviving crazy high mite loads. Some would say those are worth saving.What is an "acceptable mite count" for this time of year?
What is a dead colony this time of year?
30/300, or 20/300 is it worth saving either of those?
I would see what your counts are in the rest of your hives tomorrow and report back. If just these 2 hives are high, I would consider treating them and getting robber screens on all hives if there are no signs of virus. That they were removing brood may be hygienic behavior, a good thing. I would consider combining the two hives and treating them. If you have the option of segregating them somewhere else, I would do it. The spread of viruses is the biggest risk. J