It’s cute, but seems impractical and way out of date. There are already (nearly!) reversable male contraceptives: Vasogel (article, wiki) seems a lot further along; various other drugs also seem closer to being approved; and to me it seems that even a vasectomy reversal would be preferable to a light switch in the sack.
The problem with a switch is that switches are supposed to be switched. Like, today you want it on and tomorrow you want it off. But a reversable vasectomy (or its equivalent) probably only needs to be reversed a couple of times in a man’s life. Why install all this extra hardware for something that’s going to be switched once or twice in 50 years?
