I certainly agree with the sentiment that blacks, and all the easily offended classes, should get over it and move on. I don't see that as being a disparaging remark or sentiment.
If on the other hand, he had made remarks that were, in fact, disparaging then that alone would be enough to question his fitness for public service.
In either case, the fact a distant relative owned a slave is not of any consequence.
Thanks!
You're right the thought police should be in charge of deciding who is fit for public service.