Perhaps he took two trips to the put in. once it was floated the weight would be less of a burden and he could have taken any number of miles downstream that same afternoon.
He could have then packrafted to any subsequent point down the river or any trail connecting, taking as many days as he needed to extract himself after the deed was done.
Perhaps it is even intentionally in a place where it is relatively easy to get to, but difficult to get out of.
I've seen enough variants on the "two trips" comment that I probably wouldn't read a whole lot into it. e.g. he's quoted in one interview as making two trips in a car, so one trip might have been to pick up a boat.
It's also easy to believe that (assuming this is real), the X spot could be fairly isolated while the put-in and take-out are trafficked to the point where getting a ride back to a car might not be a big deal.
He could have then packrafted to any subsequent point down the river or any trail connecting, taking as many days as he needed to extract himself after the deed was done.
Perhaps it is even intentionally in a place where it is relatively easy to get to, but difficult to get out of.