There's a way to make an argument without calling your counterparty a "con man". I'm more on your side than the parent's side (though the idea of valuing equity at zero is illogical). I think your comment would be stronger without its first paragraph.
There's a way to make his case without calling anyone who disagrees a "shark" or a "mercenary". In fact, I think his choice of language was quite revealing of the true origins of his position; if it is not, he would do well to reconsider how it is perceived by others.
He didn't call you a mercenary. You did imply he was a con man. I know the difference seems subtle, but one is much worse than the other. Even if you disagree, two wrongs don't make a right.
