I don't agree with this just on fiat from Trump, but the USA is in its rights to give Chinese the same sort of treatment that they give the USA. If you don't play by China's rules you can't be in their market, and those rules are set up to benefit China only.
In this case TikTok is getting the same treatment US tech giants have. If that is not "fair play" I don't know what is.
https://www.businessinsider.com/nba-china-feud-timeline-dary...
In one way, it's existential: the march of authoritarianism is undoubtedly accelerated by nation-states manipulating social media.
But in most others, I wouldn't get too worked up: it's more about mundane garbage ("preserving the spirit of financial disclosure processes in the context of international capital market access") - nerd sh*t.
The US' international economic dominance is predicated on a (1) pronounced lead in certain industries and (2) a simply massive economy, which combine to (3) let the US set the rules of international "fair play." The US is where you find the thing you want to buy, and the people you want to sell to. You want access? Play by our rules - everywhere.
Tik Tok does not just threaten US data. It threatens our lead in a critical industry (1), and comes from a country that minimizes the impact of US economic might (2), meaning that China can set their own rules of "fair play" (3). Banning Tik Tok isn't to protect US data; that's totally missing the point. It's to protect the American ability to set international norms.
From that lens, this is certainly hamfisted, and I certainly don't believe views it like this, but you can damn well bet the policy nerd drafting this EO is thinking this way.