Basically, the label "Allies Matrix" is, IMO, a misnomer as it has nothing whatsoever to do with Allied Detachments.
"You can include models from any number of different Factions in the same army if you wish. Irrespective of the method you use to choose your army, this section tells you how models from different Factions fight alongside each other."
Skip a fluff paragraph, then:
"To represent this, we have several categories of alliances, each of which imposes certain effects on the game. The Allies Matrix below shows the level of alliance between units that have different Factions in the same army."
Highlighted the key parts where it says that these are rules for models/units. The Allies Matrix never mentions detachments, neither CAD or Allied nor does it mention Unbound. By using units and models, it covers both of those, as well as summoned units.