Publishing posts that are not informative, amusing or relevant for others, they are only written so that people can check in from a place. And you guessed- the place is never their home.
The better the place the post is from, the worse the post itself can be. In fact the post can even be non-existent. The answer behind these mysterious blank posts is most often simple boasting. But since boasting is present on social networks in various forms, one could argue that boasting in such a direct and obvious form is actually quite sincere and straightforward.
Be aware that not every uninformative pinned status is for boasting purposes. Some people write such posts as an invitation to others to come to the place they are posting from so they can “spontaneously” meet up.