Steins;Gate got me here... I originally thought "obtaining IBN to erase SERN's data of them" has no relation to "erasing the first D-mail and causing Kurisu to die", but I forgot that the reason the worldline shifted in the first place was because SERN got data of them (from the first D-mail). Derp.
Which means Kurisu screwed herself over by giving this idea to Okarin.