I think technically they're not allowed to take off if there's someone in a seat that malfunctions like that. If the seat is vacant, then it's not an issue. I say that because I ran into the same problem once (in coach) on what was one of the last flights of the day. The flight attendant basically said to me that she could report it, but if she did, they'd have to have someone fix it before they could leave, which a) would cause a big delay and b) might have pushed them up against timing out. I checked with the person behind me to make sure they didn't mind me reclining in their face the whole flight, and we flew.