I don't think stupidhn is advancing that logic as an argument for why Uber should be let off. I think they're saying that many people on HN are part of the (disruptive, gig-economy, resource-sharing) startup ecosystem and would be adversely affected by Uber failing, directly or indirectly; so they are either choosing to let them off or subconsciously predisposed to support Uber.

It's basically the same as the famous Upton Sinclair quote: “It is difficult to get a man to understand something, when his salary depends on his not understanding it.”

I'm not saying I agree with the point, but my interpretation is different from yours. To your point, it is somewhat similar to saying, "Why haven't we found a cure for cancer? Because too many oncologists are dependent on the cancer treatment ecosystem." It's not exactly the same, for many reasons, but there is a similar line of possibly-specious reasoning.