Well, I think it comes down to my analogy to Jon Snow. As I said “For like Jon Snow, I think Daeron can be rightly criticized for having pushed for peace too fast and too hard, failing to build enough of a constituency behind his policy, and failing to pacify the hardliners who would lead a backlash against him.” Jon Snow as Lord Commander was also a force for good until his death, but that doesn’t mean his failure to sell his policy shouldn’t be counted against him.
Daeron had over a decade to sell the Dornish treaty and he failed, and there was a rebellion as a consequence. That has to be added to the ledger – compare the lives saved by the Treaty against the lives lost at Redgrass and beyond.