Isn't that the point? The entire way he is saying that, is completely designed to be irrefutable. Since HE is saying it, there is already at least ONE person saying it, and since many of his followers will simply repeat his talking points you will soon have SOME people saying it. The entire reason to say "some people say" is really to suggest to his followers: "you should be saying this".
I don't think he is a mastermind in many ways (often he just bumbles around) but in regards to language I am almost certain that he uses these techniques on purpose.
The "no collusion" and "no quid pro quo" lines, were prime examples: He set them up and repeated them countless times--and then his followers, and then the media, repeated them. This was clearly designed to steer the conversation to set up some unrealistic or irrelevant baselines. Before he used the word, "Collusion" was never the actual word to describe the issue. So: he set up the standard: "unless you prove collusion", I am completely innocent. But "collusion" couldn't be proven, because it wasn't a legal standard applicable to the issue--and then later, when it looked like it may be possible to call what he did "collusion", they could easily pivot to "it isn't a crime" (which is technically correct.)
The "no quid pro quo" was intended to do the same: Make it so he actually has to be caught saying EXPLICITLY what he was offering for dirt on his opponents. Of course, generally no one does that (that is how in the US, you can have someone give millions to a campaign, and then the same politician enacts a law that makes that person billions--and it doesn't count as bribery, because you cannot ever prove the quid pro quo, since no one is stupid enough to actually say: "make this law for me and my contributions will be assured") Nevertheless, in this case the whole thing seems to not work out so well, because he forgot that he wasn't supposed to say it.
PS: I agree with Turtle though. Listening to ALL media (I would change it to ALL somewhat credible media--the others, one may listen to just to know what some other people are hearing) is really the best way to sort out some likely facts.