Agree, although the problem is broader.

United should do two things:

1) Instruct FAs that their baggage should go at the back of the cabin, if there's not separate storage, not the front of the cabin.
2) Install signs in the bins above bulkhead seats stating "this bin for bulkhead passengers only". Of course, if that space goes unused after boarding is complete, the FA could use it, but not before then.

The problem is not just First class but also economy bulkhead.