The whole thing where people like Caitlyn can use their range to autoattack his turrets with no retaliation is going to be a bit of a burden for him. Definitely won't be able to just leave his turrets unattended.
Attended, though? Meh, he'll be a good defender. I just don't know how valuable defense on this map is actually going to be compared to frantic fast-capping offense. One slow defender can't really take care of very many control points by himself after all.
I do hope, hope, hope that he works well there, though.