Yes, very strange. I cannot get my head around the fact that 3(!) immigration lawyers told OP this was perfectly fine. In 5 minutes of googling I found 3 links from lawyers' offices' websites explaining how it was OK to file AOS from VWP but only without such an intent on entry. I myself did this!
(I was completely in the dark about immigration processes which in that case was to my advantage, when I entered I thought I'd leave at the end of 90 days, not realizing at the time that as a spouse of a USC I couldn't just come back easily.)