I'm not sure the Persian derivation is "nonsense".
The Complete Book of Muslim and Parsi Names by Maneka Gandhi and Ozair
Husain lists Sûrî as a Persian name meaning "beautiful red rose". Perhaps "gul" is the generic word for "rose" in Farsi, and sûrî is the name for a particular variety, or perhaps we just have a case of synonyms in the same language, as with "flower" and "blossom" in English.