Desperately searching for anything ... we know. How about posting that evidence that someone successfully locked out the camera from stills? We are all waiting.
An incident has been posted. Maybe it was simply an out of spec unit. But I bet if we had a half dozen reports you would ignore it as "just forum members." And if a YT reviewer posted the same, "just a talking head shill looking for clicks."
You want to believe what you want to believe. Period.
Other people are simply wondering, and perfectly open to the possibility that the R5 is as robust as any DSLR on stills. But you can't blame them from wondering. The only reason video modes become limited with stills shooting is because the camera can't shed heat fast enough while shooting stills. If it could then stills would not eat into video time. Now maybe it reaches an equilibrium point and maybe stills will never push it into the red. But a basic understanding of thermodynamics is enough to make one question that.