Full house on 4 flush board vs tard

[Jay Riall]

In general I think your reasoning looks sound, but I think you are underestimating the amount of times he has a mid diamond and calls a decent bet but checks behind when you check. With a loose guy like this there are a tonne of pair+mid d's in his range by the river aswell as just lone d's. Check raise allin is still a pretty viable line imo, but not particularly clear cut.