C.E. Evans wrote:
If Solok truly thought Humans were an inferior species, then it is illogical for him to be associated in any kind with them (and that includes both Federation citizenship and service in Starfleet).
As I said before, it is just as illogical - perhaps even more so - to even think in the first place that humans are inferior to Vulcans. (The concept of 'superior' and 'inferior' races are, logically, meaningless. It's emotional and illogical to believe in such things. Solok, being Vulcan, is not entitled to that.) Solok obviously believes that, so it's hardly a stretch that he compounds that supposed "illogic" by joining Starfleet.
Besides, perhaps the reason Solok did that was so he could rub it in the humans' faces, so to speak. Solok believes in the superiority of Vulcans, so he joins Starfleet in order to try and prove it.
As for the T'Kumbra
: I still believe that Solok could have used his influence at Starfleet Command in order to populate his ship with an all-Vulcan crew. That way, he gets the best of both worlds: he gets to serve in Starfleet, but not alongside "filthy humans".