This is impressive. But it just strikes me as optimizing the wrong thing. A CTF shouldn't be about submission ops. Surely it would be better for everyone if all teams who send the flag within a submission window share the prize
I'd also say that this encourages people to sit on exploits instead of reporting them immediately, so they can try to submit it next time if they didn't get it, even without submission timing shenanigans.
So it may be actively encouraging the "wrong" thing as well.
That would be a different meta-game and while I didn't think deep into it, I believe the likely outcome is - people are just discouraged and won't consider submitting to kernelCTF.
