Is it a big secret that men like to look at boobs? I'd like to meet the women who were so offended by such an obvious joke. In the entire circle of women I know, I really can't think of one who wouldn't recognize the playfulness of the idea (and not take it seriously).
If a female made an app that included men's butts, would people have the same reaction?
Probably not, but that is because men aren't trying to release themselves from the clutches of institutional harassment and marginalization in tech. It isn't like you can just swap the pronouns for your argument - because in doing so, you also swap the historical context and culture, and when you do that then you come to different conclusions.
All things being equal, yes. However, men don't have women catcalling at them in the street, don't have to put up with women ogling them in public, get away with more pay for doing exactly the same work, are more likely to rise to positions of power, are favoured by many systems of monarchy, don't have to put up with other people acting as if they own their bodies and have a right to tell them what to do with them, etc, etc, et-bloody-cetera. I like the way that you think only women can possibly be offended by this kind of behaviour. - a man
When the jester mocks the king it's funny. When the king mocks the jester it's just mean.
The situation is inherently asymmetric, which makes but-what-if-they-were-(men/white/straight/etc.) arguments facile at best and disingenuous at worst.
Even if all things were equal, Tits and Sixpack apps would still be all about objectification, and I for one would be fine with that not being encouraged either.
For example of a gender-swapped situation that made the man in question extremely uncomfortable even without the history and cultural norms that excuse rape, I recommend reading about Jon Hamm's penis: http://www.rollingstone.com/movies/news/jon-hamm-tired-of-jo...