Weigel is not going to build out a news operation for an ABC St. Louis affiliation for the same reason Sinclair hasn't: There's no demand for another news operation in the market. ABC isn't going to pull the affiliation over not having news, because there's nowhere for it to go. ABC knows this. That's why it hasn't already happened, end of story.
The market is dominated by existing news operations. None of those are places for ABC to go. Nexstar is being openly hostile to ABC, Gray has been semi-openly hostile towards the networks in the recent past, and Tegna has been desperately trying to not exist for years now, and will likely become an extension of Nexstar. None of these seem like good options for ABC to even start negotiations with.
Look at Miami. They had to settle on a .2 of what is ostensibly an "independently-owned" station with an existing news department. You have to assume they went to Scripps during these negotiations, as they own both WPXM and WSFL in the market. Scripps probably said "no" to the idea of building out another news operation in Miami, because they've done it before, and it's failed every time.
At best, ABC would end up as KSDK 5.2 in St. Louis. Weigel does not seem interested in owning network affiliates as their entire business at this point is diginets. This is why the rumors frequently swirl about CBS buying up WDJT. It just makes more sense than what is currently happening.
KDNL is probably what most "network affiliates" will look like at some point, anyways. It's no secret that Nexstar and Sinclair are dreaming of a world where they control 100% of the airtime on their stations. As the networks increasingly become commercials for streaming services, I can see a future where the "Big 4" simply bounce around low-powers and diginet trees with a deal that they get to program 2 minutes of ad time an hour. The big owners won't want them, because they don't want to air an all-day long commercial for Disney+/Paramount+/Peacock.
CBS in Atlanta, ABC in Miami, and the Kimmel thing, are all symptoms of the early stages of the death of the current affiliate model. Not to mention, business analysts are starting to suggest that ABC (and probably the others) get out of traditional broadcast altogether.