The parent talk about how the building material like rebars absorbs the isotopes, and then how long it can afterward be harmful.

Do those isotopes also get absorbed, and if so, at what rate? Since I don't know the physic I don't know if all isotopes can get absorbed at the same rate, but my intuition is that the answer is no. I would also guess that nuclear plants get exposed to different amount of each type of isotope, so the above table would need to include both in order to compare the radiation risk after X years.