The point you are missing is how EU antitrust works, in the EU there is essentially a split between the Commission specifically the Directorate General for Competition and the competent authorities (aka the regulators) in each EU member state.
The DG COMP investigations are usually triggered via complaints raised by member states however they can also decide to investigate it own their own, once they done if any action needs to be taken they would authorize the regulators in each member state to take that action they do not enforce actions themselves.
However there still needs to be a violation of either Article 101 or 102 for them to investigate, this is quite different from the Chinese case where NXP and Qualcomm had to seek permission from the Antitrust regulator, in this case if NVIDIA requires one it would only be from the UK regulator and there is currently no freaking way that Brussels would interject in the midst of Brexit.
A year, 5, 10 down the line they might decide to open an antitrust case if they believe that NVIDIA's practices warrant an investigation, but currently there is no way for them to block the sale.
Nvidia/Arm merge is large enough to require the commission be notified prior to its implementation. The time between notification, clearing or final decision is just few months.
The DG COMP investigations are usually triggered via complaints raised by member states however they can also decide to investigate it own their own, once they done if any action needs to be taken they would authorize the regulators in each member state to take that action they do not enforce actions themselves.
However there still needs to be a violation of either Article 101 or 102 for them to investigate, this is quite different from the Chinese case where NXP and Qualcomm had to seek permission from the Antitrust regulator, in this case if NVIDIA requires one it would only be from the UK regulator and there is currently no freaking way that Brussels would interject in the midst of Brexit.
A year, 5, 10 down the line they might decide to open an antitrust case if they believe that NVIDIA's practices warrant an investigation, but currently there is no way for them to block the sale.