I don't know enough of the matter to have an informed view, but I think it's worth noting that there is precedent for this sort of thing. Take from one of my Python scripts:
No, you can use any program to launch executable scripts that start with #!. The kernel sees that magic number at the beginning of the file, tries to read a program path and arguments, adds the script as the last arg and executes the whole thing.
The various shells are just a subset of the possible programs used.
