Looking back on the discussion of semantics and syntax, only Phillip
Hallam-Baker has proposed anything reasonably concrete that is
incompatible with SPF. While I think some of the stuff he has
suggested has merit (e.g. open vs closed sets), I personally (my
opinion!) do not think this qualifies as being significantly better
than SPF.
It is somewhat strange that you think the proposal incompatible.
We can write an axiomatic semantics and an opperational semantics
for the same programming language that are precisely equivalent.
I think that for this particular application the axiomatic approach
leads to a better understanding than the quasi-operational approach.