He earned what "several times over"?
What logic compels you to conclude that if you get viciously and frivolously sued by someone and publicly badmouthed by him (on his weblog) you should give him a lucrative and prestigious employment (i.e. the Entrepreneur In Residence)?
Do you think a sane SV VC should employ a toxic person that publicly calls Zuckerberg a psychopat?
So far he filed a bunch of frivolous lawsuits against anyone who came into contact with him and looked at him funny. He always represents himself, so there's no cost for him but it hurts the defendants because they have to hire and pay for real lawyers.
His previous lawsuit has been dismissed by the judge http://www.plainsite.org/flashlight/case.html?id=716057
His other lawsuit (http://www.plainsite.org/flashlight/case.html?id=716056) is in shambles on procedural grounds because his California lawyer wants to withdraw from the case which would leave Greenspan as the only lawyer and, just like in this case, he sues on behalf of his company and a company can't represent itself, so his has to have an outside counsel to proceed.