Should I add a person who left my group to my evolved paper? The answer, in theory, is trivial -- add them if you think they contributed -- but there are some nuances...

1) This person (who left about 4 months ago) was a more senior researcher (not Prof. title, in fact below the Prof.) who was in charge of managing a small research group that I'm part of. This person expected to be in the author list of all papers, given the seniority, even with minimal contribution (1h meetings every 2-3 weeks where basically I explained what I was doing and was given some high level comments)

2) We did have a couple of meetings prior to the departure, where the idea (the 'direction', the 'goal') of the research was agreed upon and how it could be tackled.

3) We agreed on a possible solution that I proposed, but this solution did not work (the person is not aware of this, since we haven't been in touch since the departure) and the paper is now quite different. Even though the technique I'm using now was brought up in a conversation, I had already had the idea that it could work so it was not this person's contribution (although the person might think so because it was 'said first').

4) We have had previous arguments over paper authorship, and I gave in and added the person just to be in their good graces.

I do not think this person contributed enough, given that the initial idea was mine, the solution was mine, the paper and experiments were done by me. But I don't want another enemy in academia. At the same time I have negative emotions toward this person because I was on the receiving end of some name calling and threats during a previous argument that affected me negatively.

Thanks for any input.

EDIT: I'm a postdoc.
It is good to minimize the number of academic enemies you have. Purely as a strategic move you might just want to ask them unless it seriously offends you. That seems better than making an assumption one way or another. 

How much contribution is enough depends on a lot of things, including field and place, of course. But helping with "high level" direction doesn't sound like it is trivial. 

Of course, in asking if they would like to be on the paper you could say that the "paper has evolved quite a lot since you were last involved". 

Pick your fights for when they really matter, I think. Especially as a post-doc who wants to move up.