Ok so in laymans terms:
1) supplemental restraints are banned UNLESS installed under an approval (form 337, STC etc)
2) doors off operations where a passenger occupies a seat using an approved restraint (seatbelt) are still legal and allowed
3) to operate with a supplemental restraint (e.g. 'monkey harness') it must be of a quick-release type and approved on a case-by-case basis in the interim (no doubt until FAA can come up with a new reg)
Seems straightforward and sensible enough in the circumstances.