I feel like this assumes anyone doing a search would scan the reddit post and some unknown sites and conclude it's real. When without ai mode those would likely be skipped over and instead they'd dig into a site like Wikipedia, and maybe even check out the citations.
LLMs don't reason, so it doesnt know that the reddit post is likely an uncritical repost of the other articles. It doesn't follow the discussion to see it is (probably) debunked in the comments. All things a marginally educated human would do. AI summary raises that bar, because of ai hype.
And then there's the whole problem of how search itself has been ruined (and how a small part of that is because of how "ai" companies have behaved)