You can probably get away with it, but I wouldn't. You should just take it back apart because you probably won't stop thinking about it until you do.
I agree, I installed the same delete plates on my car, the torx screws do hold the plates to the intake plenum. Probably won't hurt anything, at least in the short term, but I would take it back apart and put them on...if nothing else...just for piece of mind.
And it's not that big of a job.