I would say the same except that in practice subs tend to be connected by longer runs, and often plugged into a different outlet, so balanced may benefit more in those situations. However, many people run subs with single-ended cables without problem. I would not use the word "only". I would use balanced if available but would not base my decision solely, or even primarily, on that feature.
Handwaving explanation: The low frequency effects (LFE) channel is specific to movies that use the ".1" channel and it is sent to the subwoofer by default. Most AVRs incorporate bass management that can route the LFE content to the L/R speakers if they are set to "large" (rarely recommended as most speakers of any size benefit from having the sub handle the LF signals). Bass management will also usually send LF content below the crossover setting from all other sources (CDs, streaming music, record players, etc.) to the sub. Note the LFE crossover setting and main crossover setting may be different in your AVR; some combine the two into one global setting, some do not.
YMMV - Don
"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley