Why are ALE and INTA not floated during Hold on an 8088 while other outputs are?
Indeed, bus ownership is the key here. Asserting INTA grants an external device permission to drive the bus, but since the CPU is not allowed to drive the bus at this point, it is also not allowed to delegate that permission.
ALE goes to a single external component that we don't want to glitch -- it's not a bidirectional signal, and tri-stating it would only require adding a pull-down resistor.