not really questionable he thought the enemy was already close to him when he planted he didn't wanna get timminged, he didn't knew enemy omen was still at B site
Idk I feel like planting open is just a way better position, cause you could play heaven, long and site and have clear sight to the bomb. While when you plant generator there are only two ways you can stop a defuse
but he was constantly watching A main that mean he thought enemy omen was already A main so why would he plant in open, you can see the enemy omen is far away as you see from observer perspective but he didn't knew that.