Earlier quoted context omitted.
Revealing my ignorance on this topic: Why would IBM care who owns their stocks, assuming the specific shareholder doesn't try to take influence on the development/direction of the company?
They don't. The parent is wrong in suggesting someone 'convinced' Buffet. Because of the herd mentality around investing who invests in you does matter, but not for this discussion.
I was thinking more along the lines of Buffet talked with people at IBM and realised that he understood the way they operated.