First, googling or searching public information is not stalking by any definition. Most of the internet is not a private space, the information available for searching is public.

Stalking would be using that information to contact and terrorize the victim or proxies for the victim.

Second point: the “experts” appear to be distorting or exaggerating for effect by using the word “slander” incorrectly or very loosely, i.e., in a non-legal sense.

See also that lawsuit Gary Condit filed against Dominic Dunne, thrown out of court recently.
Opinions formed by patients are not “slander” even in the loose sense if they are an opinion about subjective matters.