He signed up for the show cuz he liked the change of scenery, the character storyline, probably cuz he gets to play someone very different than Dean Winchester.
He didn’t agree to do the show cuz he was going to open his hole and jerk off for us!
Y’all need to stop fantasizing
While all of that is true, they show didn't come to him. He actually fought for the role and had to audition (in spite of his professional connection), which means they shouldn't have had to make accommodations to the script for him. If the role is too graphic for him, he shouldn't have pushed so hard to get it. That said, people still have VERY unrealistic expectations.