Agreed. I didn't even take the time to find out what their gender was since it's not any related issue. "Guy" was just used in a generic sense[1].
[1] http://www.quickanddirtytips.com/education/grammar/generic-s...
[1] http://www.quickanddirtytips.com/education/grammar/generic-s...
But like like guy, dude because gender neutral in common speech.
Even if we were talking about 'he', your link would be out of place. Calling out the use of a gendered default as bad is not in fact another point of view on whether it is the default.
For example, "Oh, I know a guy that knows X," "I know a guy that is a fan of X" or in a less positive manner "That guy just cut me off [on the freeway]!" (since you rarely see who it might be and their gender doesn't matter)
I could say "dude" as well, but sometimes dude might be too informal. I could reword it with a number of other pronouns, but it depends on context and whom one is talking to.