Sure, he is admirable that way. But the comment says not necessarily, which is not a throwaway. Personally, it seems to me that being good at teaching is at the least independent of being a good researcher, if not perhaps negatively correlated. That very much does not rule out extraordinary exceptions (ones that deserve a great deal of attention, for sure).
I just think they are not correlated. Both require you to put effort into being good at it. They also require you to have a firm grasp of the source material.