I think it's a relevant issue. I was never a gamer, but I can see how social isolation could feed into social problems. We enjoy our internet, we enjoy watching TV, we enjoy video games - all solitary activity. How are our interpersonal skills supposed to develop? I would be interested in seeing whether people who game very regularly have poorer emotion recognition performance or even social cognition task performance.
I'm not sure where the research is, but for an undergrad class, I found a paper measuring emotion recognition among nerds and gamers. Turns out because they're more likely to have been bullied, they're more sensitive than the norm to the emotional states of others. This hypersensitivity presumably is a reaction to needing to know when to get out of a situation, and when it's safe to relax.
This shouldn't really be a surprise. I'm a gamer, and all of my gamer friends are academically and socially successful; not a universal experience, but video games cannot be a scapegoat here. While many who play video games are becoming reclusive and emotionally/academically stunted, countless more are as successful as ever. Video games did not cause this, though it may be that they are used by those men falling into this cycle as a more modern means of escape.
It's also worth noting that video games are very frequently not, as you say, a solitary activity. Nearly all of the most popular games released during the past console cycle have included multiplayer in some form. This isn't to say that playing online with strangers equates to face-to-face interaction, but many of the multiplayer additions to modern games are meant to be played together. Split-screen has become a must for many co-op campaigns. Party games are huge, and getting bigger. Hell, look at the 5 best-selling games on the Wii (which was the best-selling console of this generation): Wii Sports, Mario Kart Wii, Wii Sports Resort, Wii Play, New Super Mario Bros. Wii. All are intended to be played with friends present. The top 5 for the other two consoles are primarily single-player, but prominently include local multiplayer.
Frankly, I have to question how close Zimbardo is to his topic, and how much he actually knows about video games; this is important only because he is labeling it, alongside pornography, the biggest factor in the "demise of guys." I haven't read his book, but from the article: "Video game production companies are in fierce competition to make games that are ever more enticing, more provocative and, now, in 3-D." I'm not convinced that Zimbardo understands video games, or has bothered to look beyond the latest Call of Duty/Battlefield AAA-game crop of titles. Yes, they are among the fastest-selling games of all time (though Diablo 3 just thoroughly unseated the latest Modern Warfare title as fastest-selling game ever), but they are not representative of the industry in any way. There is no real trend towards 3D gaming. I'm not sure what he means by provocative; sexually provocative, like the poorly received Duke Nukem 3D? Morally provocative like the controversial No Russian level of Modern Warfare 2? Intellectually provocative, like the fantastic Braid? The allegation that provocative games are breaking men is nonsense. And finally, the idea that media which is created to be "enticing" is harmful men is ridiculous. All media is created to be enticing, and that which fails is forgotten. The Avengers is enticing; 24 is enticing; Harry Potter is enticing; Magritte is enticing. The difference between these examples and, for example, the universally well-received Half-Life 2 is only user input. Is Zimbardo arguing that it is user input, a nonexistent 3D movement, and the idea of "provocation" that destroys men? If so, I truly don't understand. Perhaps it's just that these things all draw men to play; if that is the case, then someone should remind Zimbardo that people have been saying for centuries that new technology will destroy society, and it hasn't yet. Finally, his idea that (from the article) there will be some transferal of player into protagonist, warping their view of the world into one totally egocentric, is just absolute gibberish. Again, are we blaming user input to explain why this would happen when a millennium of written fiction didn't lead to the same outcome? Pressing buttons forces me into a purely egocentric worldview? Gibberish.
Blaming video games for lower graduation rates among men is nonsense, Zimbardo.