The only thing is, as far as the SOP is concerned, evidence of trimmed feathers is "Faking", which is a DQ. Obviously if the judge can't tell then you won't be DQ'd, but it's still technically "faking" (p. 30 of the SOP). Rather than trim those feathers, what about using hair tape like others do and tape the crests up so the birds can see? That way, when it's time to show, you can remove the tape and and it won't be a problem.
I am with you, though, it's something I dislike about the breed and the large crests -- I think a bird deserves to see what's going on in the world around it.