The author argues (in the comments on the webpage) that Tami had a small time frame to import her contacts, but perhaps she just didn't show up in "People You May Know" yet.
Re:LinkedIn: The Creepiest Social Network
by interactually on Friday April 03, 2015 @12:39PM
(#9316844)
Author here: You're probably right on that particular example. Unfortunately there's still a number of others that have no other explanation other than undisclosed relationships with other sites. Just the other day, I had two requests to connect from people I'm only friends with on FB; I haven't seen either of them for over a decade so I'm definitely not in their contacts list.
But perhaps the others did? If 'Steve Jacobs' imported his contacts and you exchanged emails with him, LinkedIn apparently becomes aware of that relationship. In fact:
> Tami has a total of 5 connections, lives in Seattle, no public company or title listed, but we just happened to exchange a few emails a couple days prior regarding some questions I had about software her company sold.
Tami probably used the imported contacts feature here, and that's how LinkedIn would know.