Mom0405: I was a bit mild in the way I put this to the SLP, but I'm gonna let it all fall out here: For cryin' out loud, we DO all that stuff!!!!!!! (Sorry about that -- needed to be said, rudely, not to you, but man, I just needed to say it that way) (Sidenote: I'm an artist, I worked with SLPs until I decided to stay home wit DS, I actaully know this stuff kinda ok.)
The three times thing is something I've done since he was born, and we regularly use "simple" sentances -- we just don't want to do it ALL THE TIME. "See Space Shuttle?" "See little wings" "small wings, small" just.... just... just... blark. (Actually, DS was the one who asked about the small wings... Answering why they're small in three word sentences would be even harder)
I'd be asking them for research evidence that the specific treatment they plan to offer will benefit him long-term - totally reasonable request, sounds as though they won't be able to meet it. I guess you're right that it's the difference between his receptive and his expressive abilities that's got them concerned, but I'm not sure what the argument would be that it's a problem. I think if you suddenly start using 3 word sentences to him he'll worry about what's happening to your language!
So: here's the next installment in the story. DH offered to write the email to reject the programme and accept followup instead. He wrote this incredibly "Polite," horrifically condescending letter, asked for published studies, and appended the PhD to his name

It was SOOOOOOOOOO strident compaired to what I had written first, when I was trying to be "nice."
DH is WAY better with people than I am, so I decided not to complain, and he sent it. <giggle> I hope they don't send out a hit squad.
-Mich