The press release has since been updated and a correction issued:

https://www.presseportal.de/blaulicht/pm/4971/5882017

The assembly leader of the Palestine protest camp informed the Dortmund police today that Ms. Greta Thunberg wanted to visit the assembly in Emil-Figge-Straße. Following an examination by Dortmund Police Headquarters, the latter issued an order banning the camp.

The Dortmund police carried out a risk assessment for the assembly. The announced visit by Ms. Thunberg led to the conclusion that there would be more people at the venue than stated in the assembly registration. The time frame specified in the assembly confirmation would also have been exceeded. The recent events in connection with Thunberg were taken into account in the assessment. After intensive examination as part of a risk assessment, the Dortmund police headquarters ordered the ban and the associated dissolution of the assembly.

The assembly leader announced on site that the assembly had ended and arranged for the camp to be dismantled.