The general public submitting CSAM directly would indeed be highly unlikely, but the scenario we need to consider involves those in positions of authority who can manipulate systems behind the scenes.
Imagine that an unflattering or satirical image of Viktor Orban is circulating in France, and let's say it becomes viral, inciting discussions that the Hungarian government finds detrimental to its international image. The authorities might want to suppress this image, not just within Hungary but also in the whole of European Union.
The Hungarian government - who presumably has access to the EU CSAM database (or can coerce those who do), might attempt to add a fingerprint of a manipulated CSAM image that collides with the fingerprint of the satirical image. The principle here is not for public individuals to submit CSAM directly but for government actors to manipulate systems clandestinely.