I was thinking of FAI as a typical contrarian cause, and that a respectable academic setting might be too strict for Eliezer to, say, work on the book or study math for a year.

The primary point of tenure is that it frees people up to study more or less whatever they please. Now, that only applies to academics who already have major successes behind them, but it isn't at all hard for an academic to spend a year studying something relevant to what they want to do. For that matter, one could just as easily say take a year long Masters in math, or audit relevant classes at a local college. You are overestimating the level of restriction that academic settings create.