No, that still doesn't make sense to me. The behavior of a logic circuit with unconnected inputs depends on the implementation; in typical CMOS, those floating

No, that still doesn't make sense to me. The behavior of a logic circuit with unconnected inputs depends on the implementation; in typical CMOS, those floating inputs can do things as wacky as picking up the electrical fields of nearby people. The proper thing to do with floating inputs is to declare them unknown, and for any logic operation which depends on their values to also be unknown. Most logic simulation software I've used or written has worked this way.