Our AIP RAC 9.26 says that a hold is
implied at the end of the missed approach procedure, unless other
clearance is issued. I found no clear indication of this in our
Instrument Procedures Manual, nor the Air Regulations proper.

OK, that would make sense. There has to be a concept of a clearance
limit and some sort of a default action to take there. When commencing
an IAP, the limit is the MAP, *not* the alternate airport, I would
think.

Not all these situations are lost-comm, either, the controller could
just be busy for a while, giving someone a long clearance, missed the
call on a congested frequency, etc. It can take just a few minutes to
execute a simple missed in a faster airplane. An expectation to start
right back up into the enroute structure without the benefit of little
breathing room to sort things out would be highly inpractical, IMHO.