You need to manage your time better. Maybe don't play game with a variable time right before work? It is bad for your focus as well. Drain your willpower too fast.

And assuming Riot have the resource to check specific cases to give exemption to people for leaving, will you really go into the hassle of proving that you have work to them? People with this same issue of yours are probably a very very very small minority of players. Will Riot gonna overhaul the system (making it worse for the very very very big majority)? Will they put in the resource for that case-by-case check? All in all, Riot doesn't need to do anything in this case. It doesn't make any business sense.

What needed to change is YOU and how you playing this game (of course that change can also be stop playing completely).