IMO this is a great illustration of how the word "reasonable" stops the entire legal system collapsing.
Contra proferentem is most important with "contracts of adhesion" like OSS licences that are pre-written contracts which are strict take-it or leave-it, leaving no opportunity for a party to bargain over specific contractual terms. Because the party does not have an opportunity to negotiate they may reasonably interpret a term in a different manner than the contract offeror intended.
The court would likely rule that the more comprehensive document takes precedence (exactly what the AGPLv3 intended.) Less likely outcome is that the court decides there was no valid license at all. This would technically be copyright infringement, but they almost certainly wouldn't issue sanctions because of the innocent infringer principle. Sneaky Company, Inc. messed the license writing and that makes copyright infringement understandable.
The court would have to decide the rules of construction in the contract and what to do with conflicting clauses. They would verify what Section 7 says. They would ask "Did the Sneaky Company lead the users to believe they had a license with AGPLv3 terms", was there room for confusion? Was the license ambiguity given that it was take-or-leave it style unfair to users?
The court would probably see evidence from company web site, and public communication to see how they advertised the software. If the company mentions AGPL and is vague about extra terms, it would be bad for the Sneaky Company.