If it would happen again after he got warned, i'd give him a 2 or 3 months ladder break.
Interesting, so some sort of "soft" ban, where you can't play the ladders. That makes it possible to scale the punishment case-by-case as well. I like it.
For simplicity, as a general rule, I think that on a 3v3 or 2v2 ladder game, if one player stalls, it's appropriate to treat them all as stalers.
Argument one being, they benefit from the stalling.
Argument two, if a team member stalls and they are passive (not leaving ladder + apologizing in public chat) then they are approving of the stalling.
Argument three, Further prevent stalling, by discouraging players to team up with a staler.
As mod wrote above, the game I posted seems to give them no benefit in terms of rank. In fact it would seem the stalling was done without a clear motif. In my eyes that almost makes it worse, since the sole purpose seems to be to worsen the ladder experience for others.
As another note: the new ladder rules should be changed to settings to make Surrender being accepted instant. Else another team can not accept, making the loosing team look like stalers, while the winning team is stalling.