There are a few important points here
A) there is a difference between learning someone’s seforim and how we address or categorize gedolim. Before anyone here denigrates Rav Kook or Rav Yosha Ber Zt”l first ask yourself how the gedolim of their time treated them. My understanding is that both were revered tremendously by the other gedolim of their time (ex. R YS Sonnenfeld and Rav Kook, R Moshe and R. Aharon with Rav Yosha Ber). Some gedolim may have seen a danger in what their philosophies may lead to but they held these “questionable” gedolim in the very highest esteem.
B) The danger posed by various philosophies changes over time. I think most people would agree that haskala is not a major threat to Orthodox Judaism today. It is just not where the yeitzer hara is investing right now. So too with religious zionism of the 1920s and modern Orthodoxy of the 1950s
C) UJM’s classification of “gedolim” is way off base. To put Avi Weiss, Saul Leiberman and Rav Kook in the same boat is lunacy.