From your link…
"Chris confirmed with me just this morning that when him and Roberta looked, I believe it was on the 14th (of September), the whole area was waist deep or higher in water," Bertolino said. "The FBI confirmed that yesterday that that area until recently had been flooded with water. When that water receded, obviously more things were accessible."
https://twitter.com/leisa1979/status/1451242097290498058
————
One thing I am not understanding is this trail was one he liked, but they say it was under water when searching. We have had a really wet summer in Florida…bad, bad storms daily. Why would BL have gone to this area as I am sure it was a wet mess then.