That is an inaccurate statement and inappropriate argument by Delta air lines.
First, it says it takes no position on the JB+AA agreement, but that statement is being made AFTER it's approval. It does not prove they hadn't filed an opposition to the agreement during the period of review.
Next, it says JB isn't an independent competitor of AA for the transatlantic (LHR) market because of the agreement, but JB's future transatlantic endeavors are specifically NOT part of this codeshare agreement, so they are indeed a direct competitor on transatlantic routes.