I did USNA Color Guard for 1 year carrying the National Ensign. That was 17-18 years ago, though, so things have likely changed. At the time, the Color Guard was made up of volunteers from the Color Company. We did everything on and off the Yard as a 6-man team. Based on my experience, I don't think it would be hard at all to plus up to 8 with as little as a few days of practice. Especially when you are talking about a straight march-on and a wheel-turn or two.
As for the diversity issue, poorly played by USNA leadership, but over-dramatized by Salamander. No matter how you slice it, the optics are something to consider for something this big. And it's not a "look how great the Navy is at diversity" thing. I always think about the young man or young women, maybe 10 to 12 years of age, who sees something out of the blue one day, like the USNA Color Guard at the World Series, and suddenly gets a spark of the possible to better themselves. Notice I didn't say race or gender. All young men and women, regardless of race, deserve to dream. So, as a white male (which I am), if I have to step aside briefly during a high vis event so the right mix of team can deliver that spark to a broader audience for the greater good then so be it. I would, however, call major foul if we were talking about screening or promotion decisions based on diversity. I've been in a number of boards and have seen nothing of the sort.
Still, poorly played by USNA making changes at the last minute and putting the 4 mids affected in a very precarious position with each other.