Me no see why he should talk any differently
It part of his nature not his age.
Malte thinks that even when Petrie sings Petrie's language not necessarily is a bad thing.
Nope, nope, nope.
Poor rhymes certainly are though.
LOL!

Good one, Malte.
If you ask me, I can accept Petrie's little speech problem, as long as he does it right. It was alot more settling in the sequals, but through the last few ones, his little problem has just gotten worse and worse. The writers are really pushing it to knock him off my top 10 list. They need to find a way to do it right like before.
I fully understand that it's part of his charcter, but you got to do it right, okay?
Anyways, aside from this issue, he's quite a nice charcter to have. Sure he's a scardiegg, but when it really counts, he can show just how brave and daring he can be. (How many times he goes to save Ducky is a fine example.)
The writers can make Petrie work, they just need to find a way to do it right. I feel it is one of the many things that are sadly killing the franchise. If they don't find a way to do it right, it could end up being part of LBT's downfall. -_-