Yes, for pure avgas, but any dissolved water will cause it to wax at much higher temps, and the Aztec seems to suffer from this more than most types (reportedly; I have been totally unable to establish any reason why it might).
I have never dug out any indication of a TB20/21 suffering from fuel icing, and I have flown for hours in -30C or so. Same engine type, too.
Maybe the Aztec has a fuel selector which is mounted on the airframe skin so it gets very cold. The TB20 fuel selector assembly (with the filter etc) is warmed by the cockpit. Or maybe the owner has knackered filler cap seals? Quite common in GA.