France needs to keep its independence built on centuries of hard work and long term strategic thinking. This project throws that away and makes then even more dependent on Germany for no benefit, and is in effect even giving away expertise as the article mentions.
Dassault is quite right to be "unwilling and it is frankly scandalous that the French executive be pushing for this. Macron can't leave fast enough at this point but it is very unclear whether the next executive will have more backbone...