Not sure I see that as a "no you can't". As I understand it:
If an entity, like a bank, loans money to the builder (or purchaser) of an experimental aircraft, that entity will hold a lien, possibly even the title, on it until the loan is paid off, which may not occur for years after the aircraft is flying. In this case we see that the aircraft lien holder (or even the owner) is being compensated for use of the experimental because they don't seem to be considered the "operator" for the purposes of 91.319 - and this is confirmed by the fact that (to my knowledge) the FAA has never taken action against such arrangements. Certainly title/ownership is not clear and unencumbered for such aircraft.
Since the wording used in 91.319 is almost identical in phrasing to that of 61.113, which we know isn't intended to prohibit the renting of aircraft to private pilots, it seems reasonable to presume that the intent of 91.319 was to prohibit use of experimental aircraft in Part 91 commercial operations or Part 121 and 135 operations; not prevent them from being rented out to pilots for use in non-commercial Part 91 operations.
