It'll only take him at least a month to climb back to Savior level though, its not like it will take him years to be that powerful again. Anyway, even baby Cable back then was powerful enough that when Apocalypse absorbed his life force he was able to tank the combined attacks of X factor and the inhumans including Black Bolt while laughing, Jean later managed to tap into Nathans powers and empower Cyclops which allowed him to one shot Apocalypse with Cyclops later saying that Nathan gave him power to defeat Apocalypse. So even baby Nathan was already powerhouse back then, theres no reason why Cable w/o TO should be weaker than when he was an infant.
Unpopular opinion but I think Cable(with his powers) is more powerful than Nate Grey based on feats (ignoring Life Seed). If we're talking about TP feats then Cable blows Nate out of the water with his feats of constant global mind reading, breaking through Deadpools and Irene's TP "immunity" (Irene was blessed by Alecto/Cyanide Jane, one of the multiversal Fates to be unreadable to telepaths), making Xavier and Emma with Cerebro unable to do anything to him and when he basically merged the minds of everyone on earth