First of all, cause I thought we was byke.
But to answer your question, yes and no. If Aethelwold's father had faith in him to be the next king, Alfred would have stood behind his decision and served Aetholdwold.
But if Aetholwold's father chose Alfred to be the king, but Aethelwold lurking in the cut was gonna be a serious threat to his kingship (meaning, if Aetholdwold secretly had more cunning and intelligence than his father knew he had), Alfred would have had to kill him.
It's the same with Uhtred's uncle. Uhtred's uncle needed to kill him because as long as Uhtred was alive, he was a serious threat. And he knew that even from the time Uhtred was a boy, because he was always smart and always had ambition, and when his older brother got killed, he knew he was next in line and wanted to carry his father's name and legacy.
So he was always a threat. Then being trained by the danes and actually developing a reputation made him even more of a threat.
Aetholdwold had none of what Uhtred had (training, intelligence, or the desire to truly carry his father's name and legacy) making him a nonthreat. At least, he wasn't a threat to Alfred.
Alfred foolishly didn't foresee him becoming a true threat to Edward tho. Or maybe he did know he would be a threat, but he decided that Edward would have to hold his own nuts to prove he really deserved to be king.
After all, the b*stard thinks.
He probably didn't consider Aethelwold but I think he was planning for the future threats when he made schemes to bind Uhtred into serving Edward.