You're comparing apples to oranges with an RO tour and major command tour. RO is a nuke milestone tour and the CGs are major command. Major command is meant for senior officers to demonstrate performance as they are considered and even groomed for Flag. The major command billets are decided upon every summer by the various officer communities, then signed by the Admiral and sent down to the communities to select and ultimately detail officers. A list/OPNOTE is also released detailing the early (LCDR, commander, and major/captain commands.
Major command billets - Large ships (cruisers, large amphibs, etc.), air wings, destroyer squadrons, type commands, etc.
Captain command billets - Naval installations, school houses, most shore-based commands, etc.
Sequential major command (after already completing a major command) - CVNs and more
So to answer your point, yes he has a "chance" for Flag.