Two things stand out from this statement from the CBP. One, the federal agents didn't "kidnap" anyone, they arrested a rioter. Two, the President's Executive Order he signed last month is their legal basis for doing it. Awesome.
I did a thread on the "Executive Order on Protecting American Monuments, Memorials, and Statues and Combating Recent Criminal Violence" and it's fantastic. https://twitter.com/Shem_Infinite/status/1276673763443171328
The Executive Order also goes after federal funding for states that allow these rioters to operate unopposed. That's why you see Oregon filing a lawsuit about it. It's not just about arresting the rioters, there are steep financial implications as well. https://twitter.com/Shem_Infinite/status/1276673214714970113