This reminded me that the issue related to completely trust-free harvesting is still there. By protecting every single participant you make the whole system more vulnerable. If automatic fee transfering was removed then small fish would start to care whom they give the power of delegated harvesting to. I haven't seen an explanation why it's not an issue yet.
Sorry, I don't see any problem here.
Delegated harvesting doesn't delegate to someone else. It delegates to another account that is is still your.