Their technology page is here.

I don't even see a specific mention of manned operations. All of the probe and telescope tech discussed is feasible.

I think their concept is nicely bootstrapped.

It would not be smart to launch a manned asteroid mission in a "one-launch" Saturn-V style. Or a lunar mission, for that matter. Assemble the vehicles and fuel in orbit.

An asteroid is considerably easier to land on than the Moon. In fact, it's more of a "docking." If an asteroid can be moved into a stable point near the Earth (relatively--we're talking Moon distance), access becomes even easier.

Space travel times for manned missions are an issue, particularly outside the Van Allen Belts, but it's nothing that can't be dealt with using existing technology. A manned asteroid vehicle would probably look a lot more like a small space station than a lunar module.

The space community is "political" in a sense. There are Moon-firsters, Mars-firsters, and a good number of "use unmanned probes and screw manned spaceflight" types. There's a lot of friction here.

I tend to be an "all of the above."