>>23340106
That's the whole reason the movie was made actually and why most early Heisei movies ended being AUs. Inoue really wanted Shinji to fight without holding back and to attempt actually killing a rider but the main writer Kobayashi strongly opposed the idea.
Since the producer Shirakura is Inoue's bro, Shirakura came up with the idea for the summer movie to be an AU movie where Inoue could do what he wanted without directly affecting Ryuki's plot but the movie should also include the Yui reveal, the explanation of Kanzaki's plan and the explanation of what the mirror monsters are to draw fans into watching the movie despite being non-canon.