He might actually believe its worth more. Or it also could just be an act to demonstrate that he believes the company is being run well - even if that isn't the case. Probably the salary he is drawing in is 10x larger so he is still net a beneficiary either way rather than a true investor. Maybe if he buys $5M or so then it would demonstrate that he actually believes it is worth more.
If he does actually believe GSV is worth more though, I still wouldn't take that as much of a recommendation given he has repeatedly demonstrated that he doesn't know what he is doing.