I didn’t get that vibe, and the wording of the reference suggesting writing some code at interview seems pretty mild too. You could read something between the lines perhaps, but the wording doesn’t seem unreasonable.

To me, that doesn’t seem like going out of his way to make Sten’s life harder.

Sten’s ability to then write code at interview will determine his chances for getting that role.

If not tested at interview, the new employer would presumably find out pretty quickly and the end result likely the same.

Sten isn't prevented from earning an income. He's potentially less likely to get a job for which he isn't a good fit. Perhaps that means he'll get another one instead? That pays more, so he can eat even more expensive food? I don't think it does much good to speculate about further downstream effects.