Well, at least he's honest about it. Obviously not as much shame in him as other guys that have been brow-beaten by anti-masturbation girlfriends.
For most men, masturbation is about a quick 'n easy release and has absolutely nothing to do with their relationship with their current partner, sexual or otherwise. Your roomie/friends hot? Easy masturbation material... like a Sears catalog. If women were content with the guilt-free five minutes of pounding and a nap, men wouldn't masturbate nearly as much. Even though my partner is almost always up for sex and is pretty accommodating to my freaky needs, I still masturbate rather frequently because I would be doing her a disservice if I just oil derrick'd her on the bed, rolled off and went to sleep. I respect her and her needs when engaging in intimate activity... and sometimes they just take too damn long with all the foreplay-to-foreplay cuddly shit.
And let's talk about that for a minute. Sometimes I get NSA blowjobs on the couch, but I'm not going to demand them whenever I get frisky.
And I'll second KirStang's "Stay out of my shit" comment. Seriously. I had two insecure, paranoid partners that felt completely justified in telling me what I was allowed to do/have. Ironic considering the fact that both of them ended up cheating on me later. Harlots*. I guess real sex trumps masturbation fuel, huh? Don't be a snooper if you're living in a world where your man only orgasms looking at you. Turns out reality isn't as fluffy as you'd like.
* I still masturbate thinking about them all the time.