I dob't care who controls the options - my role is not to let my personal feelings about what I as an individual think is fair get in the way of the game. My riole is simply to enforce the laws - I don't care if that means the offending team can exercise a degree of control about scrum numbers.
but
They must field suitably trained forwards if they are available.
what Law says that?
the Laws would allow the team with 14 to chop and change each scrum, substituting where necessary to ensure they have or don't have eight forwards on the pitch for each scrum as they chose... but I don't think any of us would allow that (?)