It would be nice if everyone could start by agreeing that that there's actually a nuanced discussion to be had about how "anti-competitive" a company can be, and also how that answer might change based on the size and profitability of the company under discussion. If your position is that your opinion is absolutely correct and there's no room for discussion, why post at all? It's just ideological battle.
With that said, I am naturally inclined to believe that businesses should have a lot of control over the products they create. My baseline is that I want to be as unencumbered as possible in my product vision and the experience I offer my users, and I'd like minimal government restrictions on my desired UX unless consumers' physical health or safety is on the line.
I see the choice of how third parties should be able to create and sell code that runs on a platform I have created as sacrosanct, from the drawing board, up to the day the first unit is shipped, the developer gets to decide. As my code is my own written word, it is akin to my First Amendment right to free speech. However, I'm willing to accept that somewhere along the journey from that very first prototype, to the 1,000,000,000th unit shipped, the equation shifts.
Most products, that is to say non-open source software, by their very nature, are non-trivially anti-competitive in some way. It is the same thing to say that the product is differentiated. I have a BA in Economics, but I'm a long time out of school, so I may be clobbering this definition, but "a product is differentiated in the marketplace to the extend that a product has a feature or benefit or functionality that is not equivalently provided by every other substitute in that market." In order for a product to remain differentiated, it therefore must be non-trivially "anti-competitive". Maybe it makes sense to dive into the definition of that word more deeply, but I don't want to waste your time. My point is simply that "anti-competitive" is synonymous with any market that is not perfectly commoditized. Hopefully it's uncontroversial to claim that "anti-competitive" is not fundamentally bad per se.
It's well recognized that anti-competitive behavior which at one scale is fundamental to a diverse marketplace of products and services which drives innovation, value, and consumer choice, at another scale is used to lock-out potential new market entrants, and enable excessive profitability or rent-seeking behavior. The words "monopoly" and "duopoly" usefully describes the ultimate/penultimate theoretical states of such a market, but they don't adequately describe that various ways we can approach such a limit in the real world. Apple is not a monopoly, but that does not mean that there should not perhaps be elevated limits on acceptable anti-competitive behavior on their part based on the specific facts of their market position.
I think it is also self-evident that it is an extraordinary remedy to judicially limit anti-competitive behavior targeted at a specific company in a competitive market. Indeed when we enjoin a company from making their products function in ways that are quite central to that product's highly differentiated user experience, yes it may grant choice to some customers of that product to operate it in new ways, it is also taking choice away from customers who may have chosen the product for exactly the functionality being target. This to me is an extremely heavy handed remedy, and should only be deployed against a company if it is absolutely warranted based on unlawful conduct by that company.
While the case before the judge today was simply a preliminary hearing on a injunction, and therefore not by any means a ruling on the fundamental issue, we can see this balancing act being employed in the current case. The contract that Epic willingly entered into with Apple and willingly violated is placed in one corner (blocking Fortnite) while the separate contract(s) of developers using Epic's Unreal Engine is placed in another corner. All we know today is that this judge was not willing to allow Apple to retaliate against the violating of one contract by withdrawing from the others, and that the judge was not willing to stop Apple from terminating the first contract after it was willfully violated by Epic. The larger discussion will likely take years to play out.