"Yojimbo" is a term for a hired bodyguard. The conclusion one can draw from his appearance here is that he is a normal - if highly skilled - bodyguard, and he only does as he's paid to do, as he does in all his other franchise appearances (see X, where his ability depends on how much you pay him). He's a sellsword, a mercenary, and here he's working for a faction of the Hingan government that wants its borders closed to foreigners.

That's... about all there is to it, I think.