In this specific case it's not about cognitive dissonance.
One the one hand, his implementing this strategy was fairly obvious just watching at the fight. On the other hand, based on experience, Floyd does respect his opponents after he's done with them. We don't even need to bring speculation about his caring about his legacy, hence the necessity to make this fight a worthy challenge to deserve the 50-0 mark. Because he just said what he always says in similar contexts.
Floyd said specifically that he thought he would stop Conor in the 6th or 7th round and that it took longer than they planned, in exactly the same context as explaining that his strategy was to let Conor tire himself out. So it is mental gymnastics to claim that everything that happened in the fight was all part of Floyd's master plan, and that any credit he gave Conor was just meaningless platitudes, when Floyd specifically related those two things together and stated that not everything went exactly to his plan, even if in general it worked. People aren't even just taking Floyd's word for how the fight played out as fact, but a twisted version that ignores half of what he said.
My personal opinion, and this is not a fact, is that Floyd is telling the truth that his strategy was to let Conor tire himself out, and that's why he was happy to concede early rounds, but that meant blocking and evading punches - not the same as letting Conor hit him, like some are trying to twist it. Being content to concede rounds is not the same as deliberately losing them - had Conor been worse, Floyd could still implement that strategy and won the rounds. Floyd was still aware that Conor is an accomplished professional combat sports athlete with decent power - 'letting' him land any clean punches would make Floyd a complete moron risking his entire legacy vs a debut boxer and Floyd is far from an idiot when it comes to boxing. I think Conor's unorthodox style mixed in with Floyd's age, lack of motivation and a gameplan that involved periods of deliberate inactivity followed by periods of unusual aggression was what made the fight play out like it did. But it takes two to tango, and Floyd got hit more than he anticipated, with Conor displaying some respectable, if hardly amazing, boxing technique. I could be wrong though.