What exactly do you mean by that? As in, that 'specific' trainer is capable of giving the launcher?
Other than that, I'm sure Modders will soon bring one, not to mention the hand to hand combat that Jake has, for everyone else.
I mean the game has released recently right? No rush...
Kind of insane? Why? It's been a tradition since 1. I was surprised they never added the Rocket Launcher to you're arsenal, yet as I've mentioned the book mentions you can unlock it.
But, I've modded it to have it on my inventory, in case I get bored and just wanna blow stuff up.