That’s the only conclusion that can be reached judging by their fights at Marineford. Oda hadn’t fully conceived of the concept of armament haki at that point in time, so there was no distinction between black CoA and ryou. Yet, Luffy has now been learning ryou being, it being exemplified by Sentomaru and Rayleigh, but also the Hancook sisters. Rayleigh by default must’ve used ryou against Kizaru, so in the same token so must Marco have as well. This should equally well apply to Vista as well who did attack Akainu who then commented on how him and Marco used haki; Jozu fought and hurt an equally well portrayed admiral, Aokiji. From this follows that Marco, Jozu and all have barrier haki, ie ryou, as the black clad armament didn’t exist at the time and these were among the coolest dudes around being portrayed as being able to square off with the strongest people that the marines could muster at that time. In light of this portrayal it makes perfect sense to grant them the haki that was portrayed as the only available haki at that time, as their performance in Marineford truly warrants it; Sengoku feared the real possibility of the WBP emerging as victors of the war! And still the top three have regular haki, by some people’s estimation
If anything for it all to make sense Oda would literally have to go back and retroactively grant them Ryou for the whole battle to make sense. At the time the Hancook sisters used haki, and in MF we saw the WB monster trio being hyped up as being literally able to contend with admirals and top tiers like Mihawk. For the monster trio at this point to not have Barrier haki is absolutely ridiculous from a portrayal standpoint.
It also makes perfect sense to have them be Ryou users in light of the fact that 26 years ago the WBP were kids, in their late teens or early twenties (Vista is the oldest and I think he is 47 as of now) and these same young adults duked it out with Roger’s crew for three days non-stop! It makes no sense for people to not grant these top three of WBP ryou when they’re able to square off with the pirates that were at the top of the pirate helm when they were about at the same age as Sanji, Zoro and Luffy is now. I mean who here really thinks that the BMP 26 years ago could match the Roger Pirates? Really? No, bottom line is that they have ryou! That explains how they could at the very least match Roger Pirates and fight all of marine HQ and all of the 7 warlords and still have a decent chance of winning (can try to find the panel where Sengoku literally says they do). WBP have a serious track record that warrants them having Ryo!