https://pmc.ncbi.nlm.nih.gov/articles/PMC7812885/
Temperatures during a fever can go high enough to damage cells and interferes with normal functions, it also interferes with viral, bacterial and fungal replication and other mechanics.
Not all chemistry ‘works better’ at higher temperatures with many proteins only functioning well within very narrow temperature ranges.
Sounds like he made poor choices, got Nissan into financial troubles and somehow thinks he’s negotiating on even footing with the much larger and healthier manufacturer Honda.