Given that its the middle of the winter even in Ohio, chances are he sees no biological need to rush back to the Tower. He's off hunting and doing things the peregrines do in the off-season. Also, it is just as likely he has been back to check out the nestsite but its not like spring when they want to put their toes all over what is there. He flies past, maybe sees SW and Boomer in his travels, but he hormonal urges haven't kicked in yet, so he's letting it slide - smart if he plans to be the resident male on the territory - don't waste effort, or at least not until you need to.
Just my opinion of course