my attorney also said "no"

I think there maybe no clear law regarding this issue, so differnt people have differnt understanding.

I am in same sitution, I will keep my H-4 status anyway.

P.S. One thing is for sure. H-1 can use 485-based EAD while still has H-1 status valid as long as he full-time works for his employer that sponsored his H-1.
So, looks like using EAD won't necssaryl unvalid H status