beta
I think the seme intentionally dropped the blocker so the uke would give it back to him.
Judging from the dialogue it really didn't seem like the seme knew the uke was a recessive omega. I don't know if the author is going to go the whole 'fated mate' match route, but at the very least I think because the seme was a dominant alpha, he could've probably sense the ukes recessive genes and was extra attracted to him cause of that as well.