The suhosin check in UBB.threads 7.5.9 displays the "warning message" if suhosin is detected, no matter if its the default value or adjusted way above what's actually needed by UBB.threads. The only way to disable that message (outside of editing the scripts) would be to disable suhosin completely.
The next release of UBB.threads will take care of the "suhosin warning" message much better. It will also give plenty more details regarding your suhosin settings in it's own section of the Control Panel.
Thanks for posting this feedback - every bit helps
