Since wall-charging is allowed by Blizzard that means the estimate that the top clear is several GRs higher than 135. A 12 GR buff means it would clear 150.
I have done the research.
I even posted a link earlier. Barbarians have been “average” since RoS released. Barbarians have been the top and they have been the bottom solo class. Other classes have had similar fluctuations and have been average during this time.
I do not know what ridiculous claim that you think he made. If it is about him clearing GR 140 during the PTR and the resulting lamentation change, he was right that the build was really powerful (the nerfed ww/rend build did GR 148 where two builds that cleared GR 147 and GR 148 were nerfed by Blizzard in patch 2.6.7.
The top end of the leaderboard is infested with botters. A bot can get you the gear but it can not complete the GR for you to be top 5 in the world.
I respect Ulma. He has been a high caliber player on several class leaderboards. I have not seen him comment specifically on the difficulty of the new ww/rend build in comparison to other barb builds or other class’s meta builds. He has requested nerfs to another class in threads like the one linked below.
Chris’s play time (>95%) is on barbs. I do not know how well he knows the difficulty of other class’s top builds.