Fediverse

That screenshot again proves that this person is extremely cringe, presumably a troll, but there's still no threat. At worst that's racism against Americans. Should obviously be removed by moderators from any normal online service that wants to encourage pleasant conversation, but that's not necessarily illegal.

As for the PDF, that's not a legal definition by any kind, it's a quick explainer for a law that only applies to hosting providers receiving complaints from European authorities. So yes, if the Belgian police sent a takedown notice regarding terroristic content then it does apply.

However, that regulation is mere instruction to EU states to draft compliant laws. It's not actionable legislation in itself (similar to the GDPR).

The full text of the Regulation does include this instruction for EU countries, which I haven't seen before:

In order to provide clarity about the actions that both hosting service providers and competent authorities are to take to address the dissemination of terrorist content online, this Regulation should establish a definition of ‘terrorist content’ for preventative purposes, consistent with the definitions of relevant offences under Directive (EU) 2017/541 of the European Parliament and of the Council (6). Given the need to address the most harmful terrorist propaganda online, that definition should cover material that incites or solicits someone to commit, or to contribute to the commission of, terrorist offences, solicits someone to participate in activities of a terrorist group, or glorifies terrorist activities including by disseminating material depicting a terrorist attack. The definition should also include material that provides instruction on the making or use of explosives, firearms or other weapons or noxious or hazardous substances, as well as chemical, biological, radiological and nuclear (CBRN) substances, or on other specific methods or techniques, including the selection of targets, for the purpose of committing or contributing to the commission of terrorist offences. Such material includes text, images, sound recordings and videos, as well as live transmissions of terrorist offences, that cause a danger of further such offences being committed. When assessing whether material constitutes terrorist content within the meaning of this Regulation, competent authorities and hosting service providers should take into account factors such as the nature and wording of statements, the context in which the statements were made and their potential to lead to harmful consequences in respect of the security and safety of persons. The fact that the material was produced by, is attributable to or is disseminated on behalf of a person, group or entity included in the Union list of persons, groups and entities involved in terrorist acts and subject to restrictive measures should constitute an important factor in the assessment.

However, the Regulation also refers to human rights such as freedom of expression. One can be of the opinion that it's better for the USA to stop existing without any plans or support for actual genocide. Someone expressing hate for your country isn't immediately a terrorist.