Again, I'm not here to comment on the validity of any of the former president's press conferences, but it absolutely is, without a doubt, a major problem if they are picking and choosing what they want you to hear while masquerading as a station free of any bias.
I'm curious about where you draw a line between "editing" and "bias."
The COVID-era press briefings you're talking about weren't "press conferences," per se. They were the usual daily WH press briefings that Trump decided to attend personally, instead of (as is usual) letting the press secretary conduct them.
Unless you're C-SPAN and you carry everything live, those briefings aren't typically broadcast live. Because it was the early days of the pandemic, everything was upended and there wasn't much else to cover, some networks and local stations carried those briefings for a while.
I am pretty sure, four years later, that NPR provided them to stations at a pretty low priority level - they didn't interrupt the live shows (Here and Now, in this case) that were airing in the early afternoon, Eastern time, and for the most part they weren't even offered as live anchored coverage.
This is VERY different from something like a live prime-time presidential news conference or address, which is a much more rare event and gets more extensive coverage. If it's an 8 PM ET event, the 5 PM PT rollover of All Things Considered gets replaced by live anchored coverage that's also being fed on the "Breaking News Channel" to member stations in the east. (And even then, it's entirely at the discretion of each local station to decide whether to take the live coverage or not.)
This wasn't that. It was a feed of a daily event that some stations took and others didn't. That's what any news editor does, by definition - no station has the airtime or staff to cover every event, and we ask listeners to trust our editors to make informed decisions about what stories are most worth our limited resources and our audience's limited attention.
After the first few days, there were plenty of reasons for editors to decide either to keep carrying the briefings live or to do what we do with almost all events - keep an ear on their content and provide a summary for listeners in regular newscasts. I don't think we kept carrying them live at my station, either. They were lengthy, they weren't breaking urgent news for the most part, and we often had state or county briefings taking place at the same time that were of much more immediate relevance to local listeners.
It being the 2020s, we were also guided (as I expect KUOW was) by the reality that listeners who really wanted the full live WH briefing feed had plenty of ways to get it, whether on cable news, C-SPAN, tons of streaming feeds, etc.
You can certainly disagree with that editorial judgment. But it seems to me like you're sort of disagreeing with the entire concept of editorial judgment. Nobody, whether it's the President, the governor, or the CEO of the station has the automatic right to unlimited live airtime. Preempting daytime programming is a delicate dance, because the regular programming has an audience that wants to hear it, too. That's why you have news directors and editors. Otherwise, we'd all just be C-SPAN - and there's already one of those that does what it does pretty well.