When an individual is inadmissible to Canada, it's based on legislation. The Immigration and Refugee Protection Act clearly outlines the reasons why an individual would be inadmissible.
In the example that you provided, you mentioned something similar to hate speech. Under security inadmissibility in the IRPA, there are various reasons why an individual could be inadmissible. Those include engaging in terrorism and being a danger to the security of Canada. Our officers must be able to meet the threshold of having reasonable grounds to believe that an individual is inadmissible based on the requirements of the legislation.
When it comes to information that other countries have available to them, it is relevant to their own inadmissibility requirements, which may be different from those in our legislation. However, we do have an opportunity to review an individual. If they have been “convicted outside Canada of an offence that, if committed in Canada, would constitute an indictable offence under an Act of Parliament, or of two offences not arising out of a single occurrence”, that person would be deemed inadmissible. Our officers would then work with our national security and law enforcement partners, as well as our counsel, to ensure that we can meet the reasonable grounds to believe that there is an equivalent offence in Canada and therefore deem them inadmissible.