I think you mean survivor bias, not confirmation bias.

Confirmation bias is when you only remember things that reinforce the way you think or believe, like only remembering the bad things that happen to you on Mondays and not the good or the bad on other days. I don't know what fallacy you think you're invoking but it's not that one.

In making an assertion that ecosystems evolved to depend on regular burning, you're ignoring all the species which became extinct in prehistory due to regular burning.

That's how evolution works. That part of it is called natural selection.

Any suggestion that we should disregard the last 100 years of land management science, in favor if lighting up the nearest bush every other month, is just as absurd as it sounds.

That's not an accurate description of Indigenous fire science at all. I recommend learning the science before you try to critique it. But you are right that European primitives have only been studying the ecosystem for 100 years. They've been messing stuff up for 1/600 of the time Aboriginal scientists have been collecting measurements.