Well, my reading is that the corrective action was less "add redundant safeties" and more "have sufficient process controls in place to ensure you don't break the feedback loop during pipeline work".

One potential problem with a pressure relief valve as a safety is that it could turn into a flare/blowtorch if there is an ignition source nearby, which constrains where it can be located (and requires ongoing maintenance to ensure vegetation/etc., doesn't build up where it could get torched).