There are still infinite hypotheses that would account for Jane's absence of evidence not being evidence of absence. Bob, the original claimant, could be cleaning up the gorilla poop. Or the gorilla poop could be in a park and easily confused for dog poop. Jane can only report her results and give her opinion; but that's all it is, scientifically, her opinion on the absence. There are infinite possibilities that her absence of evidence is not evidence of absence.
There is no evidence that gravitons exist; yet that is not taken as evidence of absence by physicists.
There was no evidence that the Higgs Boson existed for 40 years; that was not taken as evidence of absence.
Basically the idea that absence of evidence is evidence of absence is an opinion, not science. As the saying goes opinions are like assholes, everyone has one, and it stinks.