It is interesting that the word "option" doesn't appear anyway in the Virtue description.
Consider all these other hermetic virtues that don't work all the time, but when the character dedides so: if you have Flexible Formulaic Magic then what, you can't change the parameters of an spell that you are fast casting? If you have Diedne Magic, you can't fast cast a spontaneous spell while getting the Diedne Magic benefit, because you have to choose to divide between either 2 or 5?
Spell casting is full with options and as OneShot is insisting on rather more effectively than me not all of these are named Spellcasting Options. Just choosing a target is an option, or casting a spell standing on one leg or with an eye closed for that matter, but that doesn't make them spellcasting options.
I guess it all goes back again at what you are looking for at the table and how your players like the game to be. I kind of think that saying "no" to something should be the last resort, unless something gets definetively broken in the way. Mine are of the kind that like coming up with stuff and doing things, and tend to get frustrated when they try to do something and you hammer then down saying they can't do that nor that nor that nor that.