You're really stuck on developing for a certain clientele, and for that base, you're right. Even for most customers you're right.
It's my opinion that if the OP wants to use Flash, his site could come out looking great and be very flexible. He can even make a mirror site in PHP if he's really worried about indexing (and users without Flash if they exist anymore.) Or he can ditch Flash like you suggest and it could also come out looking nice.
Just look at lots of the wonderful sites by interactive design firms like
Big Spaceship for why I love Flash.
Of course after saying that I've recently thought my design portfolio will probably be done in html/css/javascript, but that's besides the point.