I'm not going to bother keeping up with every tweet from our cheeto-in-chief to keep track of things that might offend politically correct people this week. There is no limit to what can potentially offend others. There is a limit to how much of my attention that I wish to devote to the topic.
If that bothers you, perhaps you should reconsider what offends you. Because like it or not, "shithole" is an accurate description of Nigeria. It would not be a fair description of, say, Botswana.
I am neither telling you to stop using that word nor expressing offense. Language is complicated. Two words with similar definitions can mean vastly different things. Understanding that is part of communication.
You now know this term carries additional implied meaning. Ignoring that fact could be used to communicate a message. Similar to how some people selectively use the words "retarded" and "fag" loosely to communicate something meaningful. (Others are simply linguistically clumsy, or mean to communicate something hateful.) Depending on the circumstances, that may be what you want to communicate, completely unnecessary (thereby lowering your signal:noise ratio) or even debilitating to your argument. Knowing that implied information simply allows you to control that nuance.
Same goes for everyone else in this subthread of course.
It's a term that was recently applied, with almost comical precision, to countries that are predominantly black. It was applied in respect of the people from those countries, specifically immigrants, more specifically regarding their individual merit as potential Americans.
TL; DR When discussing race, particularly anything relating to black people or predominantly-black countries, it's probably best to use another word.