Is it just because it hasn't gotten as far as making physical predictions yet? To put it charitably it's very abstract, but I wonder exactly where the holes are that real physicists see.
Physicists won’t take a look at a new theory unless the person pushing it can demonstrate very good reasons for physicists to do so. Generally those have to be quite concrete reasons: for example explaining a known phenomenon in a much clearer or more intuitive way, or allowing the explanation of systems that weren’t easy to conceptualise of before, etc.
But ultimately it’s up to Wolfram to come up with those things. I don’t think most physicists feel he has done that, especially since the standards increase as the idea becomes more different to existing physics
FWIW, by my reading string theory is, incredibly, a lot closer to being testable than this thing, which is more like a proposed formalism in which to expess a theory than a theory itself.
But ultimately it’s up to Wolfram to come up with those things. I don’t think most physicists feel he has done that, especially since the standards increase as the idea becomes more different to existing physics