They (the EU) want to achieve a goal.. stop the Chinese government from financially helping a company allowing them to undercut competitors and bankrupt competitors who do not get government aid.
If you want to influence behavior you have to show where you want the other party to go. So you don't hit other sectors that do not have this aid.. because that would be unfair.
Game theory 101.. tit for tat. They help a sector, we fine that sector.