Takes about Jason's death that ignores Sheila's existence are always bound to be shallow. By ignoring her, you're also ignoring Jason's feelings before and during the whole situation. The singular only reason Jason ended up in Ethiopia at all was because of the possibility of finding a living relative, a mom, and ignoring that consequently means ignoring almost all of the emotional weight of ADTIF.
What Sheila represents to Jason is a chance at finding something he's been missing since his parents' death: a real family, unconditional love. With A Diplomat's Son and Consequences, Jason realizes that his role in Bruce's life is conditioned by his actions/behavior as Robin, and any child would feel threatened, scared, and insecure with such realization. Finding out he may have another mother who's alive means there's a chance he may be fully accepted regardless of whether or not he's a perfect child/Robin, that he won't need to prove himself worthy, that their mere blood relation means his mother will love him unconditionally.
That's why Sheila's treason is so heartbreaking. She explicitly denies Jason love and acceptance, she implicitly breaks the enormous hope he carried since finding out he may have a living mother.
ADITF begins with Jason hurting and grieving his parents and what they had. Every single one of Jason's actions in that comic were fueled by that grief and his need for a parent's love that, since A Diplomat's Son and Consequences, he couldn't seem to find anymore in Bruce.
By taking out Sheila out of the picture, by ignoring her existence in that comic, you automatically erase the ground of which the story sprouted from, alongside Jason's entire motivation and purpose. It becomes a whole other story that simply doesn't fit with the previous ones that led to ADITF, one that makes Jason's death even more meaningless (and Batman even more irresponsible) than it canonically already was.