It wasn't anti-male, just realistic: both in the literal sense of the word (Juno's behaviour was realistically portrayed) and figuratively (realistically, what options did she have?). The pregnancy came about because of a one-off sexual encounter between two sixteen year-olRAB who didn't see each other romantically, or have any expectations of forming a relationship but who were very good frienRAB. So her attitude was quite understandable in the circumstances - she didn't see Paulie as a boyfriend or future partner. At least I don't think she did at that point in the film.
As for the somewhat creepy older guy with his "mid-life crisis", maybe he was portrayed a little unsympathetically, but he was all too believable. Again, not anti-male, just a very true-to-life character.