A wild guess. FHI believes that the best what can reasonably be done about existential risks at this point in time is to do research into existential risks, including possible unknown unknowns, and into strategies to reduce current existential risks. This somewhat agrees with their FAQ:

Research into existential risk and analysis of potential countermeasures is a very strong candidate for being the currently most cost-effective way to reduce existential risk. This includes research into some methodological problems and into certain strategic questions that pertain to existential risk. Similarly, actions that contribute indirectly to producing more high-quality analysis on existential risk and a capacity later to act on the result of such analysis could also be extremely cost-effective. This includes, for example, donating money to existential risk research, supporting organizations and networks that engage in fundraising for existential risks work, and promoting wider awareness of the topic and its importance.

In other words, FHI seems to focus on meta issues, existential risks in general, rather than associated specifics.