Usually yes, for the right dog: combining airway work with desexing means one anaesthetic instead of two, and one recovery, in a breed where anaesthetics deserve respect. Widening the nostrils at desexing is cheap insurance for almost any flat faced puppy with narrow nares; adding palate surgery is justified when the assessment under that same anaesthetic shows real obstruction.
The honest limits: nares alone is a down payment, not the whole job, for dogs with significant palate obstruction, and a general practice should be doing this combination only if brachycephalic airways are genuinely part of their caseload, with proper overnight monitoring afterwards. The recovery window is where airway surgery carries its risk, desexing or not.
The question to ask your clinic: if you find more obstruction than expected once the dog is under, what will you do, and what will it cost. Agreeing that decision tree before the anaesthetic is what makes the combined approach work well.
Send what your vet said and quoted. A veterinary surgeon reads it and comes back to you with what they can do and what it would cost, before you pay anything. A written second opinion is from $250.
Send the case, hear back from a surgeon with what they can do and what it costs, and only pay if you go ahead.