You asked if a load required a double-pole single-throw disconnect?
You betcha. My 220v air compressor, which uses a 220v motor (two magnetic windings, one for each phase) to drive compression. It requires (and uses) a DPST switch because leaving one hot line active, the unit would try it's darndest to fill itself with air when the tank pressure fell below the pressure-switch cut-in pressure. That would quickly damage the motor — if the motor would turn at all. (If it didn't, the active magnetic windings would rapidly burn themselves out. If it did, the stress of driving a compressor expecting both active windings would also burn it out, just a bit more slowly.)
It's worth mentioning that a great many appliances that require 220v service simply don't require switching. Ovens, stoves, furnaces, air conditioners... But, then again, they're all DPST switched at the breaker box, so I suppose you could say all 220v loads must be DPST switched.