This is wildly dogmatic and not really based in reason. The risks of a relationship are evident, but what about the upside? Imagine the chance to vet someone over time for cultural and professional fit for a role that they might excel in. When a company gets large enough where there is zero interaction day to day are there no possibilities that this might work? Setting aside a lack of disclosure, is the leverage so great that someone is a liability having a social context? It just seems like people are pretty black and white on this.
Wait...let me get this straight. You're asking "..is the leverage so great that someone is a liability" for having a relationship? And you're asking this in a thread in which the OP describes how his ex-lover's attempt at extortion (if we believe the OP) has forced him out of the company?
Nope. The leverage was in his lack of reporting it, not the action of hiring a sig' other. The only thing that would serve as leverage would be emotional grief supposing that professional protocol was followed.
TL:DR Devils Advocate Postion