In hopes that this thread will actually help someone else who suffers the results of such ghastly incidents, I offer the following follow-up.
As previously noted, the bloody, greasy PD bits left what looked like oil stains on the minicell foam blocks. I had first rinsed them with plain water at the launch, then washed with dish detergent at home. When they dried the grease spots persisted. Next, I applied GoJo Orange hand degreasing gel and then washed that off. I had thought that got the stains out, finally.
Well, the spots were still there today when I used the blocks again, to go paddling. They didn’t reek like before but when I put my snooter right on them (no, I don’t know why I do things like this except maybe the dogs I used to have might have had undue influence on me), I could tell they did not smell like the rest of the foam.
That ticked me off.
Next step when I came home was bringing out the big guns: OUT! Advanced Severe Stain and Odor Remover spray.
The stains are still there. But a snoot test reveals it got rid of that je ne sais quois smell.