Supporting some policy that happens to result disproportionate racial representation is not racist. It does not support racism, and it does not prolong it.
I don't agree, necessarily. Suppose, hypothetically, you have been running a local sports team for many years, in a hypothetical all-white town. And suppose you have a strong preference for picking people who grew up in the town for the team, because (you feel) this enhances team loyalty and spirit, and garners strong support from local fans of the team. So when some black people move into the town, you don't pick them, not because they are black, but only because they did not grow up in the town.
So I think one question is, 'is having grown up in the town a reasonable criteria to set for the jobs in question'?
'Things that happen to result in different outcomes', even if not intended, can still be problematical in the same way that putting the ball in fairly into the slightly sloped table football game I illustrated earlier can be problematical.
Also, in a slightly different sense,
if a status quo was arrived at via unfair discrimination, then neutral actions which serve to maintain that status quo do, effectively, prolong the discrimination.
Hypothetical: A town decides to award business grants only to businesses in the town that have been in operation for 50 years, as a way to reward those businesses for longstanding services to the community. But historically, it was very difficult, because of unfair discrimination, for blacks to buy or successfully operate businesses in that town. So, the more recent black business owners now missing out on the financial assistance could be said to be prolonging the unfairness, even if the grants are awarded for race-neutral reasons.
It just does depend on so many things, not least what events have preceded the current situation, but also the details of the current practices. Don's scenarios are, imo, too anecdotal and lacking detail to make a considered call on. As such, while they are interesting scenarios and bring up interesting issues, I'm not sure how much use it is to meaningfully comment on them, except in the hypothetical.