Yeah I really don't get that take either. The entire point of the denouement was vengeance on Rollo who was quite obviously a diabolically evil prick. Not sure how anyone sees it differently.
I finally watched the last few episodes of the new season over the weekend (had skipped around a bit). Overall a good season, about on par with 2 and 3 for me. Favorite was definitely "Hang the DJ," brilliant concept with a nice twist I didn't see coming. "USS Callister" was a good way to kick off the season, generally lighthearted with serious undertones, and a fun, hopeful ending. I really liked "Metalhead;" I'd love to see this show tackle more post-apocalyptic scenarios in the future. "Black Museum" was fun in the way it explored various technologies, and in the end was a decent enough revenge story. "Crocodile" was well-executed and tense, but also horrendously bleak and not something I'll ever watch again. "Arkangel" had great potential and a few really good moments, but it seemed like they couldn't decide what they wanted the episode to be.