I accidentally bought some vegan cheese from Trader Joes once.  Tried it on a grilled cheese...crap tasted like mayo when you melted it.  I essentially bit into a fucking grilled mayo sandwich...flavor- and texture-wise. Anyways, there is no reason what-so-ever to use mayo in that pie.  Hell there's no reason to put tomatoes in a pie.  I wept for the tomatoes.  Can't you just eat the nice fresh tomatoes??