If he’s playing by the rules, he’s not the problem.
In fact, it makes him smart.
I agree. There’s no “double-dipping”. The pension $$ are part of the compensation for work performed previously. The pay check is for current work.
If the pensioner/employee had a private retirement plan, as opposed to the (mandatory) government pension — no one would be objecting to the employment income. Similarly, if said pensioner were to secure employment elsewhere; no one would level charges of “double-dipping”.