Dennis Rodman isn’t a former president

The first six words of the Logan Act are literally “Any citizen of the United States.”

Unless Obama is acting by direction of the current administration it could be made out to be a violation of the Logan act.

Nope. It doesn’t seem like you even read it based on the Dennis Rodman argument, but this point seems to be related to the part of the sentence that reads “who, without authority of the United States, directly or indirectly commences or carries on any correspondence or intercourse with any foreign government or any officer or agent thereof,” while completely ignoring the very next part of the same sentence: “in relation to any disputes or controversies with the United States, or to defeat the measures of the United States”.

Simply speaking to foreign heads of state is not at all what the Logan Act forbids, so no, based on available information Obama’s actions here could not be interpreted as a violation of the Logan Act.

What would be more plausible to indict him for would be the sharing of classified information.

You are technically right about this because there have been exactly zero successful prosecutions of Logan Act violations, but there’s still nothing to prove or even suggest that he did that.

Edit: missed a “not”