Univeristy revues are inherently left leaning, even if (as is often the case) most of the cast/script writers/directors/etc are not left wing. This is for two reasons:
1. The audience tends to be more left wing than right wing (they're pretty much all uni students).
2. Satire is perfect for making fun of the right wing. It's just naturally that way.
And trust me, I've seen a few revues in my time and this one was quite tame as far as right wing bashing goes. Atleast they didn't explicity tell you to vote for the ALP this time...