Current Set Up:

1 - Residential setting
2 - Cloth covered 2 conductor "romex" running inside steel conduit to
bathroom ceiling light fixture.
3 - One nut on inside of fixture box, one nut on outside, securing
threaded conduit to the fixture box.
4 - Access to fixture and conduit from above is available through
attic floor.

Goal:

Replace old light fixture with exhaust fan/light fixture. Single unit,
fan and light controlled by a single switch.

Problem:

Conduit extends into area where the new fixture will be placed. About
4" of conduit needs to be cut off.

Question:

The fan has a plastic box for the wires with 1/2" knockouts for a
romex clamp. Is it OK to cut the conduit back as far as needed and
simply let the cloth covered romex extended freely from the end of the
conduit into the romex clamp or is a junction box required so that the
end of the conduit can be secured?

If a junction box is required, is there a special connector that can
be used since the threads will have been cut off?

BTW...I have not yet seen the current set up, only spoken to my son
about the issue. I should be able to actually see it this weekend.
I've told you everything I know about the situation so far.

Thanks!