He is, however, a Radiant - which we know is Invested enough that he shouldn't be able to leave the Rosharan System.
In addition, a mistborn would be similarly tied. This doesn't seem to be an issue for Hoid, though. Kelsier, as a Shadow, would have an easier time, I'd think, since his Investiture has faded (admittedly, he probably can't leave the Scadrian System now because he held the power of Preservation).