Quote Originally Posted by Borgh View Post
So black ships collecting from those areas must make a hell of a beeline towards terra or deliver fifty year old psykers.
The Black Ships take everyone who registers as a psyker. Regardless of how old. If they've already somehow managed to control their powers, they can be immediately branded and sent on their way to whatever Hell awaits them, or they get fed to the Emperor. The Emperor cares not how old you are.

TLDR: the warp did it
Yep. Exactly. There are several mentions of the fact that time moves differently in the Warp. People can go for years in that place and not age a day. Of course, you can be in the Warp for a few days and age several months. It's a crap-shoot.

Point is, we're expected to take the fluff at it's word. Doesn't make sense? Doesn't matter. It's fiction. It works. Why? Because. That's why.