Samsung's public reasoning might be that disabling unlocking the bootloader because of the directive, but there is nothing in the directive that forces them to lock the bootloader. It does sound like a convenient scapegoat if they don't want to talk about the real reasons though.
The phone makes who end up disabling the unlocking of bootloaders are all doing so on their own accord, not because some regulation is forcing them to.
Finally, the EU’s broader right-to-repair policies makes it kind of impossible that an outright prohibition of unlocking the bootloader could happen. But of course, nuance doesn't make people click article titles on the web...
Lawmakers need to assume that their laws will be interpreted and abused in the worst possible way.
Is there anything from the current directive's text that makes you believe they didn't already? Again, this directive doesn't require them to disable the unlocking of bootloaders in any shape or form.
If the company want to disable the unlocks, they'll do so for as long as there is no regulation forces them to keep them open, regardless if there are unrelated directives or not.