Yes, perhaps it was naïve for Ukraine to assume that Musk's offer of Starlink access would come with no strings attached. Though I can certainly understand if Ukraine assumed that even if Musk tried to do something, the US government wouldn't let that happen, so perhaps the blame is on the United States.

That being said, Musk did interfere. Whether he should have been trusted not to isn't really the point—the fact that he is inclined to use his wealth to dictate international policy in this way is extremely troubling.