To go back to the original question, while there may be no ATZ at a gliding site, there is rule 17. If you are not conforming to the traffic pattern, you are at risk. Gliding traffic patterns include the launch phase, which by winch is a climb at well over 1000 feet per minute to 1000, 2000 or even 3000 feet; and a circuit which is typically descending from 1000 feet or less all round to the final approach.
Gliders thermalling away from a winch or aerotow launch may not constitute a "traffic pattern" as such, but common sense suggests that within a mile or two of a gliding site on a good day is not a smart place to transit if you can avoid it.
Chris N.