d.fear wrote:In the Codex:
SM, it says that Telion is lent to other chapters to teach them, i was wondering would he ever be lent to an
IG regiment or task force to teach them?

Putting it simply: what he's lent to teach isn't simply the techniques of Scouts.
The Scout-Sergeants teach their charges how to be Astartes, forging them into the 'right stuff' for when they become full Battle-Brothers.
Those teachings would be wasted upon the mere mortals of the Imperial Guard.