Sorry, but your submission has been removed because we don't allow hypothetical questions. This sort of thing is better suited for /r/historicalwhatif.

The Romans were xenophobes, not racists. Their empire derived its success from the fact that anyone who accepted and practiced Roman culture was considered Roman, regardless of where they were from or who their parents were. That was the ideal, at least, in practice, there was a fair amount of anti-barbarian prejudice, at least among the aristocratic elite, though this was in part because the "old money" civilians resented the noveau riche, who were often barbarians who had joined and climbed the ranks of the Roman army.

It is, of course, impossible to give a definitive answer to this question, but given the Roman ambivalence towards their barbarian neighbors I would think the answer would depend more on the aristocrat's political thinking than any prejudice - after all, killing the barbarians would mean fewer soldiers to fight against Persia and the Berbers, and to work and pay taxes on all that new land. On the other hand, trying to administer all those new subjects at once would be much harder than replacing them with proper Romans, and if all that territory suddenly becomes uninhabited then the hyperwealthy would stand to make major profits by buying it up on the cheap.