He's not dumb, but we get kind of emotional and erratic when it comes to our loved ones.
He is worried bro. He imagined the worst, that is if he was alone in a heat as a omega in a place that only monsters like human exist, who knows will happen to Etienne? He's not dumb, he just cares too much for Etienne, that he doesn't care about anything but his safety.
Bruh like the man literally just discovered the shitty treatment Ettienne went through by the hands of his own mother. It's a natural reaction to be anxious when he may assume the uncle was also involved in concealing Etty's omega traits like come on
Hmmmm....Rishar is kinda dumb. People need to put a leash on that man, like dude what if one day nobody was there to stop him from ruining Etiennes plan? My dude has a lot of heart but so little brain.