Licenses:
Stations have licenses. NBC is a network that can have affiliates. NBC owns some stations but the majority of TV stations are not owned by a network. Carrying network programming and ownership/license are not necessarily the same thing. Only in the case of stations directly owned by network. Distinction between the two is important.
I am not sure what Potus is getting at here, from the article:
"It is important to point out that what Trump is suggesting is virtually an impossibility; the FCC issues licenses to specific TV stations (many of which may be affiliated with NBC) but not to NBC itself. Those licenses come up for renewal only every eight years. While the FCC could theoretically decide not to renew a particular station's license, it is extremely rare for the FCC to proactively revoke a license, much less on the grounds that its content is objectionable."
Again, stations hold the licenses, not the networks except in the case of network owned stations. Affiliation is not ownership in most cases.
There may be other avenues concerning the network if caught in something. Struggling to see where the license plays into this except for broadcast content, maybe.