LPG Hot Water tank pop-off valve erupted - is this normal?

That is the exact one I have!

So if I am reading you correctly I'll need to replace the entire gas control unit as the thermostat itself isn't replaceable as a separate item.

Any recommended places to purchase? I did a check for sit 610 ac3 online and Google didn't do its normal "here are 30 vendors selling it". Does it go by another name?

I suppose in the interim I can run out and turn it off within 7 minutes or so. Makes for fast showers that way which isn't a bad thing on a 5 gallon tank. :-)