I'm not aware of a single motherboard manufacturer that would honor a warranty without the plastic protection cover. Any local PC shop that assembles computers probably has a box of these ya could buy one from if needed.
Please do not use the repair service of the guy who put toilet paper on cpu socket in the future.
Seconded. This is even more dangerous than not using anything at all. If the person buying the motherboard yanks on the paper they could easily damage pins and wreck the motherboard.
If I couldn't source a plastic cover locally I would remove the paper, verify the pins are okay, and ship without it inside the anti-ESD bag. You should take a couple photos of the CPU socket pins while you are at it.