Interestingly, Poloniex is registered as a MSB despite not touching any fiat currencies (unless you count USDT as being a fiat currency):
There might be no problems I guess if you do it like that.
I don't think it really matters where the hosting server is.
If you operate within the U.S. then it makes it their jurisdiction.
Besides remember Ross?
His server was in France and the feds still took an image of it.
Then what about direct trading exchanges like LocalBitcoins.com or www.100bit.co.in ? I dont think they need money transmitter license.
They are not exactly an exchange are they.
And to be honest, I do not know if they need a license and what kind of license.
That being said, I am not from the U.S. so I wouldn't know much about your laws there, but I see a lot of things.
Let's not forget than FinCEN asked Mircea Popescu to give them information about his exchange.
He has nothing to do with the U.S.
Conclusion, you never what to expect from the government(s).
There are many similarities though. Both LocalBitcoins and traditional exchanges connect buyers with sellers. LocalBitcoins also has a built-in escrow system so they handle BTC deposits and withdrawals as well.