No Satire here. The thing about the magnet in the finger is that you can not only feel metals or other magnets but with it beeing implanted near a very sensitive nerves you can feel alternating magnetic fields, for example transformers, electric powerlines etc. Thats something a magnet in my pocket cannot do. That beeing said, my magnet got rejected pretty fast and i chose not to reimplant it after that since i also had problems typing with it.
My argument for a magnet, even though it might lose magnetic power over time, compared to an RFID Chip is that the magnet implanted gives you a new sense that you cannot get without implanting it. Compared to a rfid for paying which can be replaced by a phone/watch/card without losing functionality and magnets aren't going to become obsolete by the whimps of a bank or cc provider.
Oh no it's super harmless. You can only feel it close to a source like when you feel your hand along a wall with an embedded wire running main AC. The only time I was genuinely surprised by it was when i walk past a motor in a train that was starting up but even then it wasn't annoying.