IMO if he didn't want your advise, he should not have asked you for it then.

I don't think you are being touchy - he should be able to take the constructive advice and filter thru what he wants... to me his reaction may be his way of expressing his anxiety towards the situation.
My ex husband was SF to my son for 15 years raising him as his own, and he struggled alot with feelings and the unfairness of his rights - or lack thereof...
If he has his negotiables and non negotiables defined with his girlfriend, he will be ahead of the game. Parenting, discipline, etc. that would be my only advice. What his role in the childs life will be what he will be "allowed" to do. I think alot of BM have a hard time allowing anyone else discipline their child.. I know I did, it took a long time for me to let go and trust that the discipline would be what I'd agree with... just my two cents.

I wonder if he plans to use the PMS card to his girlfriend when he's busy being not overly involved and nonemotional. Should make for an interesting step experience.

HE is being too touchy. He doesn't want to hear what you're saying because then he might have to admit that it's not what he wants, and he will have to make a choice (that he thought he'd already made). Some people don't want all the facts so they can do what they want to do, then claim ignorance later.

You went and bursted his bubble!

He is in love, and he only wants to be told happy things. My sister is going to be a stepmom soon. Two girls, 12 and 9. Will I say anything? Nope. She will never ask for my opinion anyway. I'm the older sister and all our lives it's been, "You're not my mom!" Anyway, she is so excited about getting married, nothing I could say would change her mind, and who am I to judge her situation. It may all work out just fine, maybe a few bumps in the road, but she only gets these girls EOWE, so maybe it won't be that bad. And from what I hear the girls are pretty good.

Nope, I'm not popping anyone's balloon, no sirree!