It's a shame to hear he has some personal issues back in Venezuela, maybe family members who are ill (total guess of course).
That said, his form has declined recently which is normal for a striker, so it wouldn't hurt to give Robson-Kanu a start. Rondon has started all but one of our premier league games this season so could probably do with a rest. Maybe getting the chance to come on against tired defenders might be quite useful for him.
As a side note, he has scored 17 goals in just over one and a half seasons. That is a good enough return for me personally.