I can see Cloudflare's DNS helping in the event that Row44's DNS is causing a server with a non-ideal route from their datacenter to be chosen. There's no real way to know in advance whether that's going to be the case, however, and it's very possible that Cloudflare could also end up choosing a less ideal server than Row44's own DNS.

Oh, and any effects from DNS server selection are likely going to be outweighed by all of the other factors that impede satellite internet, too.