I think it's an interesting question. It's a power climb, and ultimately that's why MVDP can keep up with Pog on it. Does Roglic generate enough pure power to stay with them?
Dumb personal comparison, but mountain biking I get dropped after some amount of time on 10%-15% + climbs by the smaller guys. Just carrying too much size to stay with them. But I generate probably 100+ watts more than them, and on shallow climbs I have to slow down not to drop the smaller guys, even just taking it relatively easy under threshold. Under 4% forget it, I have to ride at the back to keep the group together.
Where Roglic fits into that power/weight equation others will know better than I. But you need to be putting out a certain watt number to hang with those boys. That's why we see Ganna up there competing.