Very interesting. In that case, this person should consult with an immigration lawyer and find a good reason and then justify the same using an LoE.I am no expert either in non-accompanying spouse application. However, I have watched the views of licensed immigration consultants on making such application for the purpose of raising CRS. The key is to give a valid reason. The next question is what constitutes a valid reason? A reason as simple as economics is a genuine reason. There is no harm in applying solo but reason has to be justifiable.
Moreover, I personally know a person who made such application successfully, but what happened with him may be unheard of before. He received a call from Delhi VO asking him everything he had disclosed on his application. One of the question was on non-accompanying spouse, to which he responded with the same reason he had included in the eAPR.
Enclosing few links:
As a side note, they will still have to show PoF for 2 people and the spouse still needs to undergo the medical test, but I guess this was already known to them.