I watched the video but my question still remains
Let's assume then that all tags are equally interesting so you want to remove them from being visible in your graph in the way you describe. The important points to remember is that in elastic Graph the vertices are always terms and the edges represent one or more docs. Clicking on an edge will show how many docs a pair of terms have in common. To present the model you describe you'd need tag-centric docs e.g.
There are a few of concerns with this approach:
1) You probably need to write code to re-orient your source data in this fashion (see "entity centric indexing")
4) The interesting (rare) tags will not be emphasised (2 people sharing a rare topic counts for the same as 2 people sharing a common one)
5) The specialisms a person has (repeated posts tagged with neo4j) will not be emphasised in this model.
So you can do it this way, but I'm not sure it makes sense.