No it isn't. Mumei covered this very well earlier in the thread.
Why are you pretending that this is about feminists? The initial criticism was sparked during the live feed of the Rosetta mission. The criticism was from people with a vested interest in tech/STEM.
If we accept the argument from the except posted by Mumei... we should be also critical of any factor alienating women from STEM; including but not limited to bowling shirts with Star Trek prints on them... and indeed dumb bowling shirts themselves.
However, if he were wearing something more mundane like a star trek bowling shirt, I can't imagine that people criticizing the guy on this basis would gain any sort of traction, even if on a logical level it does make sense; that even wearing a non-overtly sexist shirt that nonetheless symbols the 'boys club' feeling of STEM is damaging to the prospects of women going into the STEM field.
Given how much media impressions and discussions that shirt storm has generated... and how it's played out; with a lot more people sympathizing with the guy rather than the point that the feminists was trying to make... that hasty move to criticize his shirt may in a very real sense been more damaging to the issue of women in STEM than the actual shirt itself was.
That is; the shirt gets more coverage, and the issue of it been an overtly sexualized and inconsiderate and inappropriate shirt is raised along with it, which in turn strengthens the impression that this stuff is a boys club.
Coupled with many people rejecting the notion of the shirt doing harm (or at least rejecting the manner of the criticism), and it just serves to polarize people, rather than converting minds to been more 'sensitive' and 'empathic' about these things (because that's not at all what's been demonstrated, even if that's precisely what's needed).
The issue of a lack of representation with women in STEM is a conversation that America (and all countries that are culturally influenced by her) desperately needs to have. But it's not one that should be attached to a case that involves some errant overt sexualization - because it serves to set people on guard about the whole issue, and as a result weakens the willingness of people to participate in reasoned and constructive arguments about a broader and far more important issue.
But if we are going to have this STEM gender asymmetry discussion; then it's reasonable for us to understand that it's a multi-factorial issue with iterative feedback loops that is affecting the overall motivation for females to engage in STEM.
There's a lack of positive reinforcement for starters; in the sense that there are very few positive role models in the media (fictional or otherwise)... a couple recent examples come to mind; Felicity from The Arrow and Brand from Interstellar - although those characters still play second fiddle unfortunately.
There's also cultural misinformation - the general impression that males are somehow more suited to the actual tasks involved in STEM roles.
These are as significant if not more so than the idea of the 'boys club' alienating women from STEM.
But even if we do engage in the idea of the boys club - stuff like the geekiness; a lot of that is fairly gender neutral (star trek) - only the overarching cultural associations make it more male slanted than female slanted. And in those cases - I'm not sure it's a problem that people in STEM areas can solve (other than suppressing their natural interests and proclivities).
Sure, the guys (and gals) in STEM can and should tone down misogyny and make themselves more empathic and sensitive to the needs of both genders. But in this discussion (the one about how to redress the gender imbalance in STEM), it's a minor point. A more important point (related to been empathic and sensitive to the needs) would be how companies in these fields can set their policies to better accommodate for women (paid maternity leave, subsidized day care, etc).