I agree with the sentiment, but would not be so harsh on the details. Succeeding in a different technical industry does offer some validation that they can succeed in this industry. Dismissing their achievements as irrelevant, even if true, is an unfair response to someone who sounds sincere in their desire to learn. It is OK to be a little simplistic and off-track at this point in their journey. Everyone starts at the beginning.

I would recommend completely different next steps. I think they are on the right track - using the tools available to them to get projects out and learn how to create. Because that is the key difference between where they are coming from and where they want to go: They are not maintaining a pre-existing system anymore, they are building new systems from scratch, so they don't need to focus on the "mechanics" of CS, they need to focus on the perspective change of owning the design of every piece of the system from the ground up.

My recommendation would be to work on finding parallels between their old skills and software dev. They clearly can understand a complex system, so rather than focusing on the line-by-line (which AI can do for them), they need to focus on the system itself. I'd recommend they look at existing complex projects, get local instances running on their machine, and break them down layer-by-layer to understand the pieces - DB, back-end, front-end, caching, the underlying servers, containers, and hardware, and then the front0line distributions of it all via the web with TCP/IP, DNS, CDNs, etc.

OP has an opportunity to step into this industry and pick up that overall systemic understanding that many of today's coders never even bother to learn. They can then add in actual coding skills and product skills, learn how to create with AI, and probably do quite well.