Since when are highways more important than the first amendment?
I could be upset about Hersheys and choose to organize mass theft of their candy bars from the grocery store as a protest, and that would be speech. But it doesn't shield me from the consequences of the crime of theft, nor does it mean that "candy is more important than the first amendment".
This is covered in the article. Part of the program, after 'boxing in' the protesters, is to indiscriminately arrest everyone regardless of any crimes committed. Charges will be handed off later.
This is a distant relative of the 'I've got nothing to hide' argument in favor of surveillance. In effect, it looks like just being there is enough to get arrested - and this is ignoring the fact that you may actually try to defend yourself when being pushed and prevented from leaving by armed police, maybe while breathing in some tear gas or pepper spray. You may even consider that the goal of the whole operation is to stir up violence, so that everyone has a reason to be arrested...