Yeah... see that's what we call a BS argument. You can use the same rationale to "prove" anything.
I could say that Neclord is still alive and posing as Eike, because after all Gremio came back and Eike is mysterious and has strange powers and appears to be undead. Obviously he's Neclord.
You need something to base a theory on, so far all facts are against you. As of Suikoden V, Dolph is dead, Nether Gate disbanded and nothing so far suggests that the facts are anything but as portrayed in V. And you convienently ignore all the hints that Mike is in fact working for Harmonia.