Decaying Hornbeams?

In summer last year we had a lot of bark stripping, particularly on our hornbeam trees, from squirrels.

Hornbeam has quite thin bark, and it seems that squirrels like to strip bark as some sort of competition.  I've already felled half a dozen which had been almost completely stripped, and I'm hoping that they will regrow as coppice.  If not, they weren't going to survive anyway,  I recently noticed this group of hornbeams, which I think have had their bark stripped and then some sort of decay.   I've seen recommendations that anything like this should be removed more or less immediately, but also it's good to provide standing deadwood for the creatures.  My current plan is that, as we are getting into bird nesting time, I'm going to leave them till about October this year, and then fell them.