Howdy DJ,
The direction that the material is pointing does not look correct for being a seminal plug. I would have said that it was impacted/stuck poop except that you said he pooped - and that material is
still there

.
Here's a heavy-duty seminal plug case from Mader's book:
Soaking in warm water and extra oral hydration, maybe with 50/50 (generic is fine) Pedialyte/water often helps.
A few years ago, I gave 2ml-3ml to an impacted Panther at the local reptile store and here was the result the next day

:
(Like the color of that urate chunk

.)