Just chuck it (I despise grates anyway

) the whole "my bird may get poop on something" is almost never a problem and easily fixed.
My birds never go for anything (esp food) with feces on it with their beak, though they have no problem walking right in it when there is some on a perch etc..
Most birds will avoid the grate and not go to the bottom of the cage, there may be a chance that if he can sit solidly on the bottom (like in the wild) he will go there and have fun. (Of he may never go there in his life ...birds...)
I have to disagree with most birds avoiding poop-- my cockatoo will occasionally pick up a small bit of dried poop and carry it (sometimes to clean off her cage--even though it's pretty dang clean already...other times, possibly for attention...)---She also enjoys messing with things under the grate
when she can reach them. She is pretty stable, medically and mentally (as cockatoos go...). I have seen lots of birds pick poop up and toss it out of their areas...and they will stomp all over it.
Without a grate, I have no doubt she would go down there and shred/dig/explore/nest etc (when bored). Poop concerns aside, you don't want them eating fruit/veg that have fallen and sat out for hours. I give my "too" fruit sometimes and then I take it out when it has sat for too long. Without the grate, she could just go pick up those old/nasty pieces later in the day. I still clean them out each day, but you get my point....9 hour old mashed banana on a potentially bacteria-laden cage floor might look safe to a bird, but that doesn't mean it is.
Also, just because a poop-avoiding bird thinks a paper-towel liner is poop-free and therefore "shred-worthy", doesn't mean that it is always going to be the case (given the fact that the liquid portion of poop can spread out on paper towel liners etc). They may still shred and contact dirty paper towels etc with much greater ease than they would if a grate were in place. Plus, bacteria is going to grow more easily in moist paper than on a metal bar. The surface area of an open cage bottom allows for full-foot-to-poop-contact (LOL), as opposed to the bars of a grate.
A bird that walks through poop may then touch something food-related with that same claw and ingest bacteria, or accidentally drag their tail through poop while climbing around on the bottom.
Just wipe/spray the grate each morning and evening with an avian safe disinfectant like f10 SC ....Then it doesn't get super caked on.
I have recently removed paper-towels from under my grate altogether, as Noodles was fishing them out and making confetti from them.
She also is being treated for a mild bacterial infection (discovered in a mouth swab) that my vet said likely came from shredding the corners of paper towels on the cage floor. She didn't shred the visibly poopy parts, but she got close enough...That's probably why I felt the need to write a novel LOL.