Long story short, it's basically a PsyOp. Almost all the studies that say it's bad are observational studies. There's no good hard scientific evidence that proves it's bad, as a matter of fact, it seems that actually having low cholesterol in your older age increases all cause mortality.
Discussion
Seems the Ancel Keys hypothesis from 1950s with only 5 countries was misleading.
Life expectancy correlates to meat consumption per capita: