mrs, im prety certain that while emotional SUPPORT dogs arnt supported psych service dogs are covered under the ada as long as, like ALL service dogs, they are trained to perform tasks related to the disability.
for example, for those with an anxiety related disorder a dog can be trained to "find an exit" essentially pulling the handler out of a crowd to a "safe" place...
or remind to take meds, ect...
those would be trained tasks that assist with the disability and would class the dog as a service dog...
simply "being there" kisses, hugs, petting ect is not considered a trained task even if its for comfort and helps, but as long as the dog is properly task trained psych dogs are covered...
but there is definatly a difference between psych service dog and "emotional support" animal.
this has been a realy good resource for me
Psychiatric Service Dog Society
in the case you posted though, id be VERY suprised if that dog was a service dog...generally while sometimes its nice to have a dog free night out...most people wouldnt leave their service dog alone in a hotel room...crated or not.