Being a minor shareholder in a corporation isn't a prohibited transaction or run afoul of self dealing regulations.
Even in circumstances that they would, you having less than X% of voting shares mitigates that, the X depending on what type of tax deferred or exempt entity is in question. SOME tax deferred/exempt entities have stricter self dealing regulations and even they wouldnt have had an issue here as Peter Thiel was one of several co-founders.