At 41:23, after a long, long battle, I threw a 4 sec granade across entire map. In a blink of an eye right before the explosion, the granade stopped, killing 27 hp worm. Me and Vesuvio had no way of knowing whether it was 0.25 sitter or not. It felt super unlikely to have sitter when throwing a granade across 98% of the map length.
I had 37 hp worm, so what could I do? why would I unnecessarily deal damage to myself just to later find out that I didn't cow?
It was a common sense for both me and vesuvio that we simply wait to see that granade on the replay, and if my worm's health ever goes below the damage that I have caused from that potential sitter, we would call it a loss on our side.
But it never went below 27 hp, and we ended up winning, having 37 hp in my worm. After the match has ended, it turned out that the granade sitted 0.26s before the explosion.
You might say "yes, but you didn't lose a turn, that you would usually lose for inflicting damage to yourself". Well... I did lose a turn because Korydex darksided himself by building a long girder at 52:15, making himself completely immune/impenetrable.
Since it was unclear if it was a sitter, I think it's ok to keep playing and check the situation after the game. Then put the rule in effect if needed. If you throw a sitter, you have to use a turn to shoot yourself for the same damage (or skip a turn and reduce the same damage so that you die at X HP). Losing a turn on top of HP reduction is important because it could be otherwise beneficial to throw sitters. In similar cases (e.g. unclear if a player touched a wall in WxW) we have changed the result afterwards when someone didn't skip a turn and he was 1 turn away from dying at the end of the game.
This isn't what the rules say but the best way to deal with a sitter is to deduct the amount of damage you did, from your own worm, so if you done say 45 damage, you die on 45hp, and skip turn.
It's not perfect though because sitters can ruin hides as well. :-X
What I said above is NOT part of the official rules, it's just what some of us used to do as like a gentlemans unwritten rules in cases of obvious accidents.
Because that could be horrendously abused if it was an official rule. :D
This next part IS talking about the official rules for BnG on TUS:
You dealt 44 damage with that grenade, so you should be taking 44 damage as per the rules though:
(https://i.imgur.com/eq1NIhd.png)
Just because the worm only had 27hp left, doesn't mean you only take 27hp damage, it dealt 44hp so it was game over the second that grenade hit like that.
It's technically a win for TdC.