At all costs, Robin will avoid getting hit with the light. Seeing how the domestic disputes that the team had been sent to clean up--messy disputes, which months of counsellings may fail to assuage--have a source with the strange weapon, Boy Wonder figures that there's things he wants to keep to himself.
If Bart, Cassie or Kon fall victim, Tim thinks he can live with any of what they'd be forced to say. Inhibitions and basic social skills keep a lot of thoughts buried or unrealized. The beam wouldn't cause physical harm so the safety of the team is not in question. The attack just loosens lips, and quite throughly.
Precisely the reason Robin wants to stay clear.
He needs them. He
needs them more than they know. And they've never realized that he
knows things about them. Could use them. Would, if he had to... What
he wants could destroy them.
"You sure handled everything pretty seriously," Cassie will say to him.
Bart will bite his lip and look flustered, or hurt. Kon won't stop apologizing.
And Robin. Robin will say nothing.