If they stop being an emperor and go solo, their threat level ofcourse falls down. They dont have their empire in that case mate! Look at how much resources every single Emperor has, look at how many troops WB pulled into Marineford with and tell me with a straight face that those influence doesnt count when talking about WB's threat level.
Emperors have influence. True. But bounties don't include much related to this influence. If that was the case, every Yonko should have same bounties given all yonkos are in a deadlock situation for decades. But that was not the case here.
At the same time, Luffy became yonko and Kid/Law didn't become one even though all three have the same bounty. That extra influence Luffy had didn't helped him gained extra bounty over Kid and Law.
Luffy being a dragon son didn't help him gain much bounty and at the same time, some extra bounty was given to him after WCI only because he has a grand fleet and is a brother of the second in command of revolutionaries.
So yeah, while on occasions we have cases with influence included in the bounty, there are occasions where the influence factor didn't account for much.
Do you think Rayleigh threat level fell down because he was not sailing with Roger? I mean Kizaru thought it would be tough to arrest him even when Rayleigh past his prime. Do you think WG reduced his bounty or took back the bounty poster because he was not a threat or an active pirate anymore?
Point is stronger individual not associated with government is always a threat for them, doesn't matter whether the said person is active or not. Only way he stops being their threat when either he gets captured or when he is dead.
