I would not necessarily say that mansplaining is sexist, as males tend to do that with other males as well, neither it's even necessarily a gendered thing, but mansplaining can be annoying, because it is
annoying, especially if the person is not very rational and don't have the ability to empathize with others, as Sol is the case. He just wants to have arbitrary authority so he can impose his will and dominate others (and because he's so desperate for authority, he can't "think outside of the box", he must also follow other
authorities to a tee, such as "official", authoritative Socionics texts. Thinking outside of the box is risky and dangerous, because it might make you fall out of being authoritative).
Of course, his skewed understanding of others make him think that "Fi types" are automatically willing to accept his "perfect" Thinking, and if they're not receptive to it, then it must be because they're "evil Fe types".