You don't have to be invited. Almost all executives who care for their careers are on Linkedin.
In addition the successful ones pick and choose their jobs and don't join cronky dysfunctional organizations.
Time will tell us how Mr Cleaver performs.
Correct and being on Linkedin should not be a factor.
I had a friend who was on Linkedin once and the profile they had was not accurate. Personally, I would not put much stock in the Linkedin connection.