I doubt that Vince McMahon has much of an opinion regarding Ric Flair one way or another. I would say that he was probably pretty pleased with the send off he gave him in the match with HBK, and was likely pissed off when Flair followed this by heading to TNA. For about five minutes. Then he probably said "oh well" and that was that. It's not like TNA poses any threat whatsoever to WWE, and even if they did, it's not like Flair would be a significant component of it, so I doubt Vince feels any ill will toward Flair for his move down south.
Truth be told, if they had any friendship whatsoever, he probably feels pretty badly for Flair. Flair's supposed financial hardships are well publicized, and he probably thinks it is a shame that this old man is so strapped for cash that he has to still attempt to compete at his age and his degree of physical degradation. Either that, or he may think it's sad/pathetic that he is unable or unwilling to step away from the business. Either way, he probably feels a strong sense of pity for this man who was once such a legend, but is now a shadow of his former self, still trying to function as if it is still 1980. I know I do.