You could find a guy saying "yeah I totally made that up". Or at least trace the origin of the rumor, and note that it doesn't plausibly connect with Osama's life. Or interview a bunch of people close to him who say they've never heard anything like that, and note that it's therefore implausible that a bunch of Americans somehow know. Or find the real reasons that he hated America, and note they're vastly more plausible and documented. Etc, etc.

This is a classic "Russell's teapot". We should not give any epistemological weight to unfalsifiable things. To debunk them, it suffices to demonstrate that there was never any evidence to begin with.