For that, you might as well just use the regex functionality in man itself too. But that misses the point.

The goal of grepping in that snippet is that you're `less `ing through precisely the parts that matter, and no more, rather than wading through the whole man page, and you're using -C to control how much context you (think you) need around the search results. This is a much better setup for skimming through potential hits than going through the man page wall of text.