It seems that the problem was started when the EU commission's Deputy Head of Unit Interinstitutional & Outreach Views Ricardo Cardoso made the mistake of confessing that he had a Playstation and the Commission was working to make sure that Call of Duty would be playable on it.
His exact words were: "The Commission is working to ensure that you will still be able to play Call of Duty on other consoles (including my PlayStation)."
This seems to suggest that the Commission is not exactly playing fair and is launching a huge investigation into the deal just to force Vole into putting games on Playstation so that Commissioners don't have to buy an Xbox. It was a pretty stupid thing to post particularly as it is difficult to see if there are any other negative consequences from the sale.
The Twitshow that followed had the EU Commission rushing to replay and pointing out that Cardoso is not involved with the review of the Activision Blizzard acquisition and was "only tweeting in a personal capacity."
The fact that the Commission felt necessary to make a statement at all does make it look a lot more significant. The Commission also did not rule out that Cardoso was reflecting its thinking and it wanted Call of Duty on their Playstations too.
The EU continues to review Microsoft's effort to acquire Activision Blizzard. Phil Spencer, the head of Xbox, and PlayStation boss Jim Ryan have traveled to Brussels for interviews and comments.