I think it's it's because there are no boundaries or hard lines on what wouldn't an alpha or omega would go for in their heat/ruts if they are desparate. For example Greyson said something about having sex with Bliss his own brother to Chase. It may have not been said seriously— looking at his personality, but what I gathered in other stories from this verse there seems to be a lack of natural repulsion (compared to other omegaverses) towards beings other than a potential mate in serious circumstances.
Not saying its common though I think the author just revealed that its a possibility. I hope this makes sense
Also Chase was delirious and to him its alrieady truamatizing to go through a rut since he never liked the idea of going through one. He thought he went crazy during his rut and had sex with any living thing that was close had a hole yk?
i understand that like chase has trauma but like... why would you ever believe the asshole brother in the first place my guy. wasnt he known to be an awful person or did i imagine that?? like why are we shocked he lied gnskgnskfn