I have been slogging through the some
220 responses and came across a
response from the NTSB:

http://www.regulations.gov/contentStrea
mer?documentId=FAA-2015-2147-
0137&attachmentNumber=1&disposition
=attachment&contentType=pdf

"our main concern was to ensure that
gliders are detectable by an aircraft
equipped with a traffic alert and collision
avoidance system (TCAS)"

Gliders are already kept well away from
air carriers by Class B and C.

That makes the primary beneficiaries of
the ANPRM private jet owners able to
afford TCAS - $30K to $200K before
installation.

As long as they're transmitting ADS-B,
anybody with PowerFLARM knows
exactly where they are from several miles
away and can avoid.