That doesn't mean anything, points are kept for 2 years.
That is golf (except they aren't kept, they keep depreciating). In tennis 2-year ranking was just a suggestion from Nadal, nothing more. Points drop off after 12 months. Robin S hasn't played in the last 12, so no points. Still doesn't mean he's retired. When he comes back he'll have injury protection so he can enter the tournaments he wants, or else he'll certainly get WCs left, right and centre.