They were setting Olly up for weeks to be involved in the assassination. However, I would've preferred had Thorne not been involved. It was a little too obvious. I think it would've been a nice twist had he come running in trying to save Jon - in keeping with his recent depiction as harsh but fair.
Incidentally, Harington was announced in the trades today as replacing Robert Pattinson in a movie. Coincidentally, it co-stars the actress who plays Melisandre. I don't think too much can be read into his being cast one way or the other - after all, Peter Dinklage, Sophie Turner, Emilia Clarke and Nikolaj Coster-Waldau have all balanced Thrones duties with high-profile movies.
Incidentally, Harington was announced in the trades today as replacing Robert Pattinson in a movie. Coincidentally, it co-stars the actress who plays Melisandre. I don't think too much can be read into his being cast one way or the other - after all, Peter Dinklage, Sophie Turner, Emilia Clarke and Nikolaj Coster-Waldau have all balanced Thrones duties with high-profile movies.