Long known, he says, meaning long assumed without basis in fact. Where is the evidence that RCMP surveillance was not focused on  Russian spying and on the Canadian groups who favoured Russian style Gov't. in Canada and were willing to act secretly to achieve it.
Canada did not have a Special Branch until after the defection of a Russian Diplomat who revealed the extent of Russian secret activity in Canada, and against Canadian Embassies including recruiting Canadians to work to achieve Russian  objectives. 
Canadian defensive efforts at the time in the context of those days were perfectly legal and logical. Historians who wish to judge the past could use a more balanced approach.