You played this hand perfectly, and id call fwiw. It's such a ridiculous bet, i think he can have a worse two pair/1pair hand alot and possibly some missed diamonds/other airballs. If he turns up with 78/JQ, take a note he overbets the pot with the nuts on the river.

Judging by his willingness to chase draws with insufficient odds you'll win your $ back and more pretty quickly, providing he stays at the table.