Well in their defense. At the time that the Exodus was made, I doubt Jerome Blake's followers looked like techno-weirdos.
I can sympathize with those SLDF soldiers. They were serving the last vestige of the dead Star League, securing Terra for some yet unknown brighter future (and making sure it didn't end up in the hands of a Great House lord, those folks who (arguably) let the Star League die as a result of their own naked ambition), and obeying Kerensky's orders in the case of some units that stayed behind (not sure if the 151st Royal falls into that category).
Even when the techno-weirdo side did start to become apparent, what was the alternative? The next several years were dominated by the holocaust that was the first two Succession Wars, with nukes flying and planets dying, and the old Terran Hegemony worlds being gobbled up or destroyed all around them. Leaving to join one of the Great Houses probably wasn't that appetizing to many. Standing guard on Terra and preventing the Great Houses from getting their greedy hands on it probably seemed like a high calling at the time.