I agree with you: where no licence exists it can be argued that there is
an implied licence giving permission to distribute (or else the author
would not have uploaded it).
However, for some of the material at the IF archive, there *is* a
licence that explicitly denies anyone permission to distribute it for a
profit: see my article <GDR11.95Oct24154636@stint.cl.cam.ac.uk> for some
examples (there are many more).
-- Gareth Rees