I don’t think I said it was stupid. It just wasn’t the Win Now button it was presented as.
This was explained in-comic. Gontor’s intent was to delay Durkon in the expectation that Durkon would stop to cure the blindness — in short, that Durkon, being Good, could be manipulated into stopping and helping his family. Had Gontor dominated a victim instead, it would have ... what? Given him an ally he couldn’t use inside the blue barrier. Given him a ally that couldn’t stop Durkon. If the assumption is that Durkon is Good, then Durkon wouldn’t have stopped to fight his family member, even if the domination had held. Durkon could have stepped into the blue barrier close at hand and been 100% safe from attack, and the dominated guy couldn’t have taken any further effective action.If one of your group is blind, harmed or energy drained then no one has to take a hit and the group still get's to attack the vampire without anyone missing.
Blindness was probably just a sign that Gontor hadn’t refreshed spells in a long time and was out of really good options. Wall of Stone would have been a much better idea than Domination: retreat to the meeting place and fill in the intervening ring with solid rock. At least, if he had the time and freedom and presence of mind to make perfect choices. The fact that Gontor stayed to gloat, summon a monster, and get drawn into a fight are just signals that Gontor was a person, not a CPU.