Skunk-poison health-drops stopping

[MrTPenguin]

I was in a four-way inter game yesterday, where two worms were skunked. Around the time sd was supposed to start, the worms stopped losing their 5 hp! A couple of turns later, these two worms were the only ones left for sd and their healths went down to zero as usual.

Why did the poison stop having its effect? I'm thinking it must be to do with sd, but I've never seen this before and I can't find anything online about it.

[HHC]

replay 

[MrTPenguin]

It happens after 23 mins.

[WTF-8]

As far as I can tell, poison takes no effect when SD timer is already red ( = pre-SD time has expired, buy a full version...) but it doesn't activate yet and instead allows a few other teams to take their turns. In this case, those "extra" turns will not trigger poison damage. I wonder why.

(It's just from what I have observed some time ago. I might be completely wrong about everything, but anyway...)