This is the danger. Propaganda is not the issue. Illegal speech is. Speech that incites violence, reveals classified information, or endangers innocent people.
Lemmy is not a company, but if, for example, Lemmy starts posting the names, addresses, and home security details of Brazilian officials, you can rest assured they would block those instances as well.
X being a single corporate entity gives it different responsibilities because it operates as a business, but either way, the platform flouting the law will and should be blocked. Free speech is not a free-for-all and has limitations.