Spoiler Warning - Hammer and Bolter Episode 6 - AMAZING

[BLACK BLΠFLY]

They are the worst for sure.

[phoenix01]

Also, keep in mind that to the Imperium's mindset, there's just eldar, and few are able or willing to recognize a difference between craftworld and drukhari and corsairs and harlequins, especially when the craftworld eldar in black are willing to work with the Imperium, but the craftworld eldar in green slaughtered an Imperial colony.

[The Pounder]

Yeah, like phoenix01 says they’re all just degenerate xenos filth!

[crazyterran]

Could also only have a tentative peace with the Ynnari, this craft world could be not Ynnari aligned. Heck, could be anti-Ynnari and Guilliman was doing it to help the Xenos aligned with his cause

[Captain Idaho]

Unlikely Guilliman would act as an agent of Eldar. The short story where he seeks to remove his armour shows he has very little loyalty held for Xenos like Eldar.

[BLACK BLΠFLY]

He wouldn’t it’s just not even possible.

[redmapa]

A lot of people saw the events that brought Guilliman back and read into it some sort of Eldar alliance or less xenophobic Imperium, even in the campaign book themselves and in the BL books Guilliman still distrusts the Eldar and the Eldar's reason to bring Guilliman back was simply to give the Imperium a better chance as they take the brunt of Chaos, thats not a reason that speaks of friendship or alliance, its just giving the guy you're using as a human shield a better shield.

[Vinny]

Could also only have a tentative peace with the Ynnari, this craft world could be not Ynnari aligned. Heck, could be anti-Ynnari and Guilliman was doing it to help the Xenos aligned with his cause

 

I bet this is probably the case.

 

I also imagine there may be a Aeldari-Tau Alliance (ATA) in the future at some point. 2022 prediction.