I don't see why that would be an immoral restriction.

I don't think it's a reasonable restriction, but unreasonableness doesn't make it immoral. At the same time, if you make an agreement not to program in a rental and then you program, shouldn't you need to stop or leave? I might have moral concerns about how one enforces a restriction against programming, it's probably intrusive

Now, if your question is no programmers and/or no overnight guests who are programmers and/or you can have six tenants in the unit, but no more than three who are unmaried programmers... Then my moral compass is pointing towards no. Restricting the practicing of a profession on premesis seems fine, descriminating against the practitioners is ick.