The bike shop owner's statement that she was not allowed to take any photos of the bike or the home is evidence that Archie is fake. It is more likely that the Sussexes are simply trying to protect their privacy. They have been very private about their family life since moving to California, and they have not allowed the media to photograph Archie. This is their right, and it is not something that should be used as evidence to support a conspiracy theory.
The Sussexes have released photos and videos of Archie in the past, so it is clear that he is a real person. The fact that the bike shop owner was not allowed to take photos of Archie does not mean that he does not exist. It is more likely that the Sussexes simply did not want their son's image to be used for commercial purposes.
I think it is important to be critical of information that we find online, especially when it comes to conspiracy theories. There is no evidence to support the claim that Archie is fake, and the bike shop owner's statement does not change that. The Sussexes have a right to privacy, and we should respect that.