You can gently open it up and see if the cut extends into the cords. If so, then booting might be warranted. But if not, there's zero issue and no reason to boot. It's the fabric plies that give the tire it's strength and shape. The tread is there to protect the fabric and provide traction, but provides no structure.

Imagine the tire as your arm. If the bone is broken or cracked you put a cast on it for support. But with a cut, you only treat the cut, but the bone doesn't need help.

Off to the side this way, I'd do nothing at all, since the odds of a fresh assault in the exact spot are pretty low. If you have a tread cut more on the rolling surface you can fill it with rubber goo to close it up. People have had good success with something called Shoe-goo which is pretty cheap.