@Eaty
I'd be curious to understand what timestall rules will be in place if this comes into effect? Is this to replace the existing rules, or will it be implemented as a supplementary measure to help avoid it?
If it is a replacement, this can still be abused. Theoretically, what you are suggesting allows someone to time stall for up to 5 minutes, with the intention of forcing the opponent to dc (or /surrender when implemented), knowing that thereafter they will need to make 15 second decisions, if their opponent waits it out.
Something to think about.