Because imo, the initial does not mean anything in the grand scheme to Im. This chapter even supports that Im is okay with certain D, i.e. Vivi for whatever reason, and they were supposed to be Celestial Dragons at one point.
What matters is your actions. Garp has been kept alive because of his God Valley actions, even though his son and grandson are literally some of the most wanted men on the planet.
What is wild is that Ace did not have the luxury due to Roger., and was executed because of a blood relation. Theres a ton there we just dont know yet