That attack was clearly over the line.
It can be hard to tell where to draw the line though. For instance, for right or wrong, a candidate's sexual orientation very much is an issue in American politics because of the current battle for gay and trans rights. Video game playing is irrelevant nearly all the time, but if Congress was debating or thinking about a bill that would impact the computer game industry, her being a vid-gamer is actually quite relevant to the conversation. Politics is complicated, nuanced, and it's not always easy to see where the line between what should be public knowledge and what shouldn't be when it comes to candidates. But attacking because someone has a hobby that you don't approve of is silly, unless there's something that at lot of people would consider troubling about the hobby. You know, that the hobby might show something troubling about the candidate. Now maybe the GOP and/or Congresscritter are out of touch enough to think that vid-gaming is troubling. Or maybe their political calculus indicates that they should attack her on that front so old people are less likely to vote for her, since the elderly are often xenophobes.
It was still a silly attack, but I can think of scenarios where the GOP might have thought the attack was worth the risk. On the other hand, it was almost certainly an attempted ad hominem - instead of attacking her platform, they're attacking her to make her platform look bad.