This information is from the Texas vs Johnson supreme court case about flag buring. Is there a fallacy in this statement and if so what kind? thank you

The result of the Texas statute is obviously to deny one in Johnson's frame of mind one of many means of "symbolic speech." Far from being a case of "one picture being worth a thousand words," flag burning is the equivalent of an inarticulate grunt or roar that, it seems fair to say, is most likely to be indulged in not to express any particular idea, but to antagonize others

As written, the syllogism is valid:

Flag burning is the equivalent of an inarticulate grunt or roar, therefore is free speech.
Johnson cannot legally burn a flag.
Therefore, Johnson's free speech is being infringed.

It is not necessarily a sound argument, though; some might question whether flag burning is only free speech, or is something more. I think people would agree that expressing your opinion with spray paint on the side of a building is not just free speech, it is also vandalism. So, in the case of flag burning, I don't think it can be outlawed solely on the basis of destroying a flag. As long as no other laws are being broken (i.e., the flag burner owns the flag, and the burning doesn't violate any safety regulations) then flag burning needs to be permitted, even though it is more than free speech.