Allied Astropath

So i'm reading the rulebook faq for another reason when i come accross this line

P. 7 of the rulebook FAQ
Q: Do modifiers that apply to such things as Reserve rolls, apply to
units from an allied detachment? (p124)
A: No.

So. i've read this a dozen times and it appears to me that, an allied contingent containing an astropath gets no benefit from his reserve roll modifiers... but the PRIMARY detachment would?

I know this seems against rules as intended, but... there it is?

"an allied detachment" = a detachment that the astropath's detachment is allied with. RAI. But I totally get what you are saying.

I know we have harped on GW before for lazy editing, poor phrasing etc..... But they have now had to FAQ the BRB, the Chaos codex, and (coming soon) the DA codex due to big obvious error and poor wording (the Nob/Paladin "character" shenanigans, Look out sir basically being re-written, wrong points and options in the chaos dex and the DA codex has some major typos (Belial is missing his Iron Halo in one of the listings.)