Not sure why this indicates he believed his ideas were bullshit... in my opinion, leaving material behind to spread his ideas after his own death suggests a truly held belief, not a purposeful scam.
It would seem like they got people to believe that The End Was Nigh and that they should commit suicide to avoid said End (Yeah, hold on to your logic there). If he truly believed that it was the end, why would he need to stay behind to tend to other things?
That seems like picking nits, though - these people clearly weren't the best and brightest in the first place.
The earth was being "recycled". That's why they wanted to hitch a ride on a space ship. So, yeah, end of the world is coming so kill yourself so you don't die.
Read their material - that does not appear to be accurate.
While they did appear to believe the world would be "recycled" and potentially that this means a lot of people would/will die, the excerpts on their website does give vague descriptions of ways that people can be "protected and 'saved' from the approaching recycling". The difference would be that these people would still be "stuck" on this world, though they could "one day find them a member in the Level Above Human".
Consider the similarity to the idea in christianity of the Rapture, where some christian sects expects certain sets of "true believers" to be "raptured", while the rest - believers and non-believers and sinners of all kinds alike - are "left behind", with various means of eventually being saved:
The "recycling" or "spading under" of civilisation from Heavens Gate appears to be a form of the Rapture, with the possibility that many good people who have just not advanced far enough can survive, while the "true believers" are raptured. The difference being that in their version, it appears they believe in some sort of cyclic history for the earth, where there will be another opportunity at some point in the future.
