He's under a direct financial incentive to claim otherwise.

If AGI is reachable in 5 years with today's architectures, then why would anyone fund his pet research in novel AI architectures?

To have an alternative? So far the work on transformers was done in a large part in the open (except OpenAI which tried to be as closed as possible). There is zero guarantee that whoever discovers the path to AGI decides to publish the paper etc. It's just one of many reasons (a less important one IMO) why research into novel AI approaches is valuable for humanity.