I believe the implication is that if AI is really The Second Coming (or First Coming, if you prefer), then banks would want to keep the debt and the potential gains of said debt. Or rather, there should be an overwhelming demand for said debt.
It’s not necessarily a statement about AI, it’s just finance and accounting.
If the market is already crammed with sector-concentrated debt (because of the amount already issued), finding buyers for more is going to get increasingly hard.
At some point everyone big already has enough exposure and isn't interested in the risk of more.
The only thing that keeps the party going is being able to drain that debt off bank sheets, but it's hard to see a ton of interest in fixed rate, capped upside exposure to a high risk industry in an environment of rising central bank rates.