if you combined it with Petunia’s seemingly earnest insistence at having personally witnessed magic, it probably would
As far as simply testing the nature of reality, I’d still say no. However, Harry cares about his mother and wants his parents to stop fighting. This is what justifies the test, IMO.
The letter alone would probably not make the existence of magic worth testing.
But if you combined it with Petunia’s seemingly earnest insistence at having personally witnessed magic, it probably would.
As far as simply testing the nature of reality, I’d still say no. However, Harry cares about his mother and wants his parents to stop fighting. This is what justifies the test, IMO.
AAnnd that the result is bound to be entertaining no matter what.