No, two guys touching each other does not mean they're gay. In my own opinion, two guys are not officially gay until they develop feelings for each other...Although that doesn't necessarily mean that guy-on-guy sex still means they're straight. But that's not what's happening here.
You must not get out much if you've never heard of straight guys masturbating together...And I know I don't get out a whole lot, so if I kow this, you guys must be hermits or close to it. There's nothing wrong with guys of any sexuality masturbating together - a person can have the most active and perfect sex life of anyone else on the face of the planet, and they would still masturbate...It's got nothing to do with his wife. Perhaps he doesn't ask his wife to watch because he doesn't want her to see his friend, or maybe because she isn't aware of the fact that guys do this a lot and she would be freaked out by it.
But, from what I could tell from his original post, he and his friend were not touching one another, but just masturbating in the same place to the same thing. Nothing's wrong with that.