This might just work... (Wild Animal/Jump up)

[duckwing]

The player may also declare a Block Action while Prone which requires an Agility roll with a +2 modifier to see if he can complete the Action. A successful roll means the player can stand up for free and block an adjacent opponent.

If we're going to go to be picky over semantics a succesfull agility roll let's you stand up and throw a block. So if there are no adjacent players to block you can't stand up.

that's why you have to perform a Blitz Action to do the trick.

Yes, that's the effect of it.