Alternatively, Samsung is using that law as an excuse. If the law - and the directive enforcing it that came into force on August 1st - really applies to all manufacturers, then why have no other manufacturers followed Samsung’s example? The linked article says
A report points out that this likely due to the European Union law 2014/53/EU which imposes new cybersecurity requirements on device manufacturers like Samsung. They must ensure that the devices they sell in Europe block the installation of unauthorized software and only run signed and approved ROMs.
But it does not link to that report. My guess would be that either
- that report does not say what the article claims it says, and / or
- that report is wrong.
Unfortunately, without a link to the report, we’ll never know 
Given all that - in particular the fact that no other manufacturer has blocked bootloader unlocking, or said that they will do so, my opinion is that
- the linked article is ‘clickbait’, spreading unfounded FUD and paranoia;
- the consequences for Jolla and SailfishOS, whatever they are, will only apply to ports for Samsung devices.