Comment by kmeisthax

The problem with "oh, but wait, this merger actually improves competition" is that mergers are a contagion. A large competitor's mere existence creates an economic imperative for more mergers. This happens both horizontally (across multiple firms) and vertically (up and down the supply chain). When you get big, you can start stripping your vendors' and customers' of their profit margin, which means they need to get big to compensate. Even if a merger might have positive competitive effects, it still spreads the contagion. Which is a problem, because anyone who doesn't or can't get big will get fucked. That includes individual consumers and workers.

If the problem is that Chinese companies are shipping train firmware with backdoors, then you need to ban those companies. Problem is, given the Newag situation[0], I don't think they can actually do this at the level of individual procurements. So they need specific EU directives banning this behavior and explicitly adding a process by which procurement can ban suppliers for prior noncompliance. What facilitating an illegal merger will do is reduce the EU's bargaining power with industry, ensuring that we get more backdoored trains and more risk.

[0] Short version: they got caught shipping firmware that bricks the train if you take it to a third-party repair shop, even though the contract specifically mandated Newag provide repair manuals. EU agencies and member states do not have the power to disqualify Newag from future tenders for failing to adhere to prior ones, so they keep winning contracts