Whether they are interested or not, they aren't the only person that will see the reply. Sea-lioning seems to work best when people have left their reasoning out. For a site like this, sea-lioning at the base level is probably a public service. It's when it's used against people that have already explained themselves that it's problematic.
Honestly, I heard it for the first time within the last week myself. While I'm sure it is a problem in some cases, so far I've seen more people complaining about sea-lioning than actual cases where it was both obvious it was being used as a tactic and negative.
As for Trump, maybe I could see it if he didn't stumble or fail to answer half the time, and come up with a controversial and ambiguous answer the rest of the time, and didn't spend of lot of effort communicating what seems like the opposite of his official answers on his own time? He's not the kind of person it's easy to say has a specific opinion or stance since he's contradicting himself constantly and revising earlier statements by saying they were jokes, but then later they were jokes but not really.... So who knows.
