The LolScience made sense! Hollows working as a poison to Quincy was hinted during the Isshin flashback... But! Kubo has a lot to sort out! How come Kirge (the nazi Quincy in HM) was totally fine after absorbing a powerful hollow when hollows are poison to them?
Or perhaps the subjugation/absorbtion drains only "pure" reishi, somehow filtering the incompabtible parts during the process? How it might do that that, while still making him take on the physical properties of said Hollow does seem a bit.. suspicious.
Beside that little inconsistency, my issue with this chapter is that it seems to mark the first time that Yhwacht has done something that seems utterly inpractical and falls to the usual main villain idiocy department. Why on earth would he order the Sternritter to kill the captains with their own Bankai? Yeah sure, extra humiliation and all that, but that does not seem a very justifiable reason if you could just crush them in a fast and expedient manner without resorting to theatrics.