Author here. Thank you for pointing this out! I actually did not know that this phrase had such a specific meaning. I had incorrectly inferred from other usage

Author here. Thank you for pointing this out! I actually did not know that this phrase had such a specific meaning. I had incorrectly inferred from other usage that the phrase meant that the fact in question was supported by evidence to a degree that warranted no further debate. I feel a little embarrassed for the misuse. However I'm all the better off for having been educated on its proper use! Thank you.