Just because it says the terms are not legally binding does not make it so. In fact, I would not be surprised at all if having a short explanation invalidate it. Very risky.
I'm not sure how this differs from a preamble, which are often non-binding in and of themselves. That said, preambles do convey the intent of the agreement, so if something in the agreement is contrary to the intent... you could make an argument that there wasn't a meeting of the minds.
To the extent that the preamble and the legal text say the same thing in different ways, I think the company may be in a stronger position to enforce it. However, as you say, if the preamble contradicts the terms, then it's harder (if not impossible?) to enforce the contradictions.
In the end, it'll be a specific case and a specific judge that causes the interpretation... and other things such as representations of the service and any correspondence between the parties may also be taken into account.
