'Side curiosity: many of the SECG/X9.62 seeds contain the ASCII text 4D696E6768756151 75 = "MinghuaQu" (a Certicom researcher), sometimes shifted by half a byte.'
I don't see any mention of that in the article.
The seed for P-224 uses a timestamp from 1998, and they also said the four binary curve seeds were timestamps from 1984 that were doubled - someone did srand48(time / 2) not srand48(time).
Did the P-224 seed get updated later / was not provided in 1997, or is there some other reason for this? Otherwise, it looks like one third of these values need additional excuses to get them to map to the time range in question...
So yeah, it seems plausible P-224 and the B-* curves were generated at a later date.