The way you've described it, both sides are engaging in suboptimal communication.
Alex wrote an email to Bob which said Bob's incorrect information wasted Alex's time.
Alex should say what the effect of Bob's information was, and what leads him to think it was incorrect.
Bob replied that his information was correct and provided some supporting reasons, thus putting the blame back on Alex.
If Alex feels that his "time was wasted", then presumably something bad happened based on Bob's information. Bob should find out what it was (although, Alex should have said it to begin without Bob having to ask) and address that. Simply citing reasons to expect that a claim will be true can come off as dismissive if someone has personal experiences that contradict the claim. I'm reminded of an episode of 30 Rock in which one character notes that the roof is leaking, and another character responds "No, it's not. We did a study."
Alex doesn't find this explanation acceptable because he thinks the information is not true.
Alex has already stated that he thinks that the information is not true. Simply repeating that claim doesn't address Bob's response.
Alex believes that Bob's reply is just to protect himself from the higher officials (in the email cc), since they would be taking decisions based on the information in the email.
You don't make it clear at what point the cc's were added. If there were in Alex's initial email, then it's quite reasonable for Bob to consider the higher officials to be part of the intended audience of Alex's initial email; it's rather silly to present higher officials with a claim, and then pretend that there is something untowards in Bob wishing to refute it. On the other hand, if the conversation was initially between only Alex and Bob, and Bob cc'd the higher officials, then that does create the impression that Bob either was directing his response to the officials, and wasn't trying to resolve things with Alex directly, or was concerned that Alex would bring the officials into it and wanted figured that it would be more favorable to him if he got his side to them first.