They do get it, they're just blinded because the idea of selling Sepp as the underdog in an intra-Jumbo battle is the only story left in the Vuelta. I mean, it's hard to be the underdog when you're riding for a team that's riding roughshod over the race and destroying the mountain stages like this, but the wins that Sepp has compared to Rogla and Vingegaard mean that there is at least some kind of story there.
The other problem that they have is that Jumbo have managed to lose GCs by not controlling breaks before and giving the wrong rider time (Giro 2019), and by sitting in and trying to minimise effort to save energy for later, only to then afford others enough free energy to make them pay for it (Tour 2020), so they may be more wary of playing "defend Kuss' lead" in case the three GTs hit him and hit him hard, à la Simon Yates in the 2018 Giro or Tom Dumoulin in the 2015 Vuelta.
Rogla and Vingegaard may be scrapping over who is the one to pick up the pieces should Sepp falter... but they aren't about to not make gains just to keep Sepp protected, lest they themselves falter.