Wolverine gets credit for recognizing his own limitations and the value of the team. He realizes that he is entirely the wrong person to help Professor Xavier learn to control his power, but that in a sense within his own mind are the memories of the older Professor Xavier, the person who can help. Since the younger Xavier is able to see into Wolverine’s mind, he is able to find the older Xavier in the memories.
There are two problems with this; both relate to that question about why it is bad to contact your past self.
Wolverine remembers a version of Xavier who does not yet exist. That Xavier has come to terms with how to use his power, and has taught many others how to use their own. The younger Xavier finds wisdom in that encounter with his future self. He even quotes himself a few minutes later–when he says to Beast, “Just because someone stumbles and loses their way doesn’t mean they’re lost forever” he is repeating what his older self said in Wolverine’s memory. We have a small predestination paradox, but it is easily resolved: Xavier could have picked up that thought anywhere, and that in this version of history he learned it from himself does not become a problem since once he knows it its origin is almost immaterial. He perhaps loses the thought process which brought him to that conclusion, but in time he will fill the gaps.
The other problem, though, takes us back to the question of how this works. Immediately after this encounter, future Xavier comments that he had a glimpse of the past, strongly suggesting that Xavier’s mind reached Xavier’s mind through Wolverine’s mind. We had gotten comfortable with the notion that Wolverine’s mind had in a sense traveled to the past, and thus we can accept the idea that the young Xavier finds Wolverine’s image of the older Xavier within Wolverine’s mind. However, if the young Xavier has reached through Wolverine to the mind of the older Xavier, if the two connected across time, we have a separate time travel event with a second time traveler–one of those two Xaviers carried information from the future to 1973, and changed 1973 in the process.
It complicates our situation significantly, but reinforces what we already recognized: the idea of the film, that the brain in the future is on a moment by moment basis controlling the body in the past, has serious temporal implications (akin to those in Frequency but considerably more complex) not easily resolved by any theory of time. If we accept the possibility of this future mind/past body connection, it is not more difficult for Wolverine’s decades-spanning mind to become the conduit for Xavier’s thoughts. It just makes it much more difficult to make sense of a time travel event which already does not work in any way that makes sense.