Corsairs allies matrix

Corsairs treat Eldar, Harlequins and DE as Battle Brothers, and cannot ally or be allied with Necron Chaos Demons or Tyranids. Not come the apocalypse, never can not.  The following sentence states that they treat other forces as desperate allies and are treated as desperate allies for them.

If one where to circumvent the banned detachment rule such as through malefic spells, how would the units interact per the allies matrix?

Do they become desperate allies per the followup sentence?

One assumes.

This may confuse matters, but do units from Conjuration powers count as Allies?
Sure, they come from Codex: Chaos Daemons, but do they actually count as part of a Chaos Daemons detachment?
I had a look through the rulebook and couldn;t find reference to them counting that way for the purposes of allies, etc. I always figured that regardless of who actually did the summoning, the Daemons would just count as part of the army they were summoned from (for the purposes of allies).

Pretty sure they still count as having the Daemons faction for rules interactions.

It even gets more complicated if you summon Khorne Daemons. KDK or CD?

Chaos demon. They have DI so are NOT ever KDK.