Yes, this is RAW legal. It's also something that a GM should really watch out for - in general, you should make sure that at least one of the aspects generated is something that you'll be able to compel against the PC, in addition to whatever positive uses it might have.
It's also a good thing to consider banning, or allowing on a trial or case-by-case basis only.
For an example, one of my PCs has been toying with a high-end sponsored magic transformation ritual; I've ruled that it grants one free tag on each of the following six aspects:
Frostbite's Favor; Thirty Foot Wingspan; Dark Form, Dark Thoughts; Glacier's Implacable Might; Empowered Shadows; Power Is An Aphrodisiac
Could the player cast this in the middle of combat? Sure! It's only a complexity 18 ritual; that's totally doable via thaumaturgy-with-the-speed-and-methods-of-evocation - if you're willing to take a good half-dozen points of sponsor debt (remember, The Dark Powers Are Always Willing To Help!)
Alas, the character is demonstrating a reasonable amount of paranoia about how he uses the spell. And I was so looking forward to the opportunity for compelling collateral damage. Oh, well. Maybe later.