Yeah, it's not great.

I'd look to explain it as part of the flight of voters from the Liberal party, but would people who were turned off by Dutton really choose to vote for One Nation instead?

I think, unfortunately, it's probably genuine gains by PHON, and unlikely to just evaporate at the next election.

if his stories are to be believed

As a general rule, you shouldn't trust what a One Nation candidate says about anything.

It's unclear if any of the biographies cited in the article would have been verified before being posted by those organisations. He did give a lecture on ransom at the Australian Army Research Centre, which would seem to be an indicator they judged him as credible in that area.

It's an unusual feeling to see a One Nation member who appears to be competent. Almost certainly a bad sign.