"Regulation expands to fill the space available" is a physical law of
government.

Regulators given a task will keep at it, until they hit a limit. If
they're regulating an existing industry, either the corporations or
their customers will eventually push back when the regulations reach a
tipping point. For our almost nonexistent industry, we have no
substantive mass to push back with, so any regulatory train set in
motion will likely continue going well beyond what we'd consider to be
logical limits. So we have to be *very* careful what paths we start
the regulators down.

The only safe task to set before FAA is disclosure (ala food labeling,
or campaign contributions) so that anyone buying a flight is fully
informed of the risk.

What's not safe: enforceable medical standards and any "other"
standard that might appear to be a good idea to the fine professionals
at the FAA, whom I admire.

Why not medical standards: The medical conditions of the 500 or so
previous space travelers are secret. NASA is obsessive about
protecting all astronauts' medical privacy. Yet, the only logical
course for the FAA is to attempt to gain access to these very
sensitive records, and then make its own judgments about what they
mean. Rocket companies will *not* get to see them in detail and thus
will *not* have any way to influence their interpretation.

So what standards will the FAA adopt? Only conditions that have
failed to disqualify astronauts will fail to disqualify private
passengers? What about a condition that's OK for an astronaut who was
30, but the proposed private passenger is 60? Still OK? We all know
that many of the private firms' initial passengers will be older
because they've accumulated the most money, and their grown children
aren't responsibilities anymore... yet older people take more pills
and have more medical conditions. Do you want to be arguing with FAA
doctors about the medical status of most of your passengers, based on
a medical database you can't examine yourself... while trying to
equate the strains of a Shuttle or Apollo flight with whatever
stresses you believe exist for your perhaps quite different vehicle?
Yikes!

So consider the above for the straight-forward issue of Medical
Standards. Now consider what can happen if any "other" standard can
be thrown into the vetting of passengers.

Full Disclosure for Informed Consent -- that's how it is done when
testing risky new drugs, and it's the only sane way to approach the
issue of the government's role in passenger space flight.