So I pulled out the valve and it turns out that the sealant had completely stuck the tube to itself. That's what caused the blowout near the valve.

I was initially hopeful I could just repair the one hole and be OK, but it turns out that the 12" of tube I pulled out of the casing was ALL stuck together. Evening trying to pry the tube apart with my hands was not working. I've now read some other people who have had the same problem. A big bummer for a tire that barely saw the ground anywhere but the CX pit.

I think I'll get after Tire Alert for a repair....