In the first place, that’s not the name of a saint, it’s a family name. In the second place, it’s not decided by Google hits: his name was Saint-Exupéry, and whether people spell it with or without the hyphen or abbreviate “Saint” has no effect on it. It is what it is.
To be clear: actual saints’ names do not have hyphens. Other names based on saints’ names frequently do.
Found one more hyphenated saint in French: Saint-Sylvestre, the French term for New Yeat’s Eve.
Again, that’s not a saint’s name, it’s a name based on a saint’s name. The saint is Saint Sylvestre.