I'm sure there is a lot more to the story but the dude was called in because he sort of resembled the pictures and a Karen min wage worker thought he was a little sus... Add in that she immediately tried to claim the reward.
Also, the sheer amount of damning evidence found on him is incredibly suspicious... That was all in his backpack... The day after they found the backpack in central park full of monopoly money. Absolutely nothing about this manhunt and suspect makes sense. Even accounting for social media misinformation this whole thing is almost too much satire to be real.
He even praises Elon over it...