MC-8930 shouldn't be working as intended

Look at MC-8930. Lava/water placed onto a single water/lava source block substitutes the water/lava source block instead of changing it into obsidian. Is this reasonable? It violates the basic rule of how water and lava should react when in contact. Should MC-8930 be resolved as WAI?

I've been questioning this all the time under MC-8930 and both my duplicates (MC-129434 and MC-129543), but none of you has responded. Usually when I have an unreasonable explanation you would rush to correct me, but no one has pointed out where I'm wrong about this particular issue, and you don't reopen MC-8930 either. I don't know why's that so.

Hope that you can carefully consider this again. Thank you!