Initially it should be pointed out, as a defense supplier to USA Deus has enough subtle backing of his own.

Besides that, the entire point of what he did, is that it was a tiny wartorn hell hole, that absolutely noone else cared about.
We got plenty of examples of the great powers mostly not caring about what goes on in Afrika.
So its quite plausible him being around as there were a regime change would only illicit a "meh".
Its not like any of the great powers did anything before the former Dictator had a heart attack.
So weird if they would move in when his son took over.

Besides that, IF he had then accidentally stepped on a few toes of some minor politician somewhere.
Then the important part is, that the size of said powers military budget isnt significant.
Whats significant is what slice is available to whoever he is dealing with, and how large a % of it
they can spare on this particular insignificant part of Africa. Since quite likely there are plenty of other,
actually hostile agents to kill, and politicians to bribe, and vacation homes to buy.
So in the end, it should be quite easy for Deus to have local superiority in "this" country.

That was then of course. Now meanwhile he has build up his country.
And is to entrenched to remove violently.