AFAICR the Oldvuvai theory fails to consider some societies might try to reduce their per capita energy use since not all of them are motivated by consumption. And, then, a post-industrial civilization can either be a MadMaxesque one, a Solarpunk one or an Automated Space Gay Communist one.
Note: If that theory actually asserts those points please let me know I'm wrong, I don't remember all the details.
Why of course I'm not saying is false nor based on wrong assumptions. As you mention, the impossibility of infinite growth had been consider either by Malthusians, the Tragedy of the Commons and is the ultimate sign that capitalism is doomed to fail.
What I was pointing out is that AFAIK the main data used for some graphs is based solely on the per capita energy use worldwide, and that's why the peak takes place just before the "Oil Crisis" of the 70s. I ignore if there are national or regional metrics which compliment the theory or if there are some evaluations about potential post-industrial outcomes. I'm not doubting that it points out an imminent collapse, it's just a sincere doubt I have about these points within the theory.