But, hey, my character was the Capt. Kirk of the Realms - he didn't care if the girl was green, black, pink, striped or had six arms...
... The six arms things could be a problem. The grappling to prevent romantic entanglement could become difficult.
Really there's nothing wrong with canon individuals making appearances, and there may be points at which it fits well. The problem is the maturity of the players or their characters when it comes to it. If a mage who has his 3rd spell level wishes to duel Szass Tam? Ehh, funerals can make for an interesting set piece.
The real issue is establishing that your characters are the first to attack them. This isn't exactly Elminster's first time at the minotaur rodeo, he should be expected to go above and beyond the pale to make that encounter horrendous for the party. And why would you put a kill-happy group near such temptation?

Slainte,
-Loonook.