One of those photographs you posted found[1] to be taken by personal photographer of Trudeau and most of them taken away from protesters.

This[2] is one example how protesters react when they try to infiltrate the actual crowd.

[1]: https://twitter.com/stobione/status/1489320295764660228

[2]: https://twitter.com/MrAndyNgo/status/1488325761572478981