On Sunday, May 4, 2014 1:49:41 PM UTC+1, Uncle Peter wrote:

Chances are it wouldn't start squirting precisely as someone walks past.
If it's already squirting, they would avoid it.

The nature of a PRV opening is such that there'd be no warning and be of very short duration. Chances are indeed low that it would occur precisely as someone walks past but many 'accidents' are often the result of an unfortunate occurance of multiple instances.

Besides which, why not curve it to the wall? The PRV opening should be neither regular or persistant and so shouldn't cause damage.