It is indeed difficult to see details on your pictures.
Anyhow, I think you should let it go. Not because you are right or wrong, but because do you really want to waste more time on this?
Extech has done a classic rhetoric move, citing an authority, the IPC inspection document, and an inspector. You would now have to argument against these. The first problem, getting the IPC document, it is expensive. The second problem, going through the document. The third problem, it is for sure a few hundred pages. The forth problem, it likely refers to 10, twenty or even hundred documents of similar size. The fifth problem, they all cost money, too. The sixth problem, all the documents for sure contains parts that are subject to interpretation.The seventh problem, they for sure contain some exemptions hidden somewhere, only known by the experts. The eighths problem, there are for sure optional or alternative parts in it, and you don't know which options or alternatives Extech did chose.
Do you start to get an idea what this harmless citing of an IPC document really means? It is now their expert against your expert. You do have an expert at hand, don't you? And I don't mean some random guys on the Internet.
Do you really want to start arguing that the burns are burns (IMHO not permitted, but I am not an IPC-A 610 expert), or only discoloration (IMHO partly permitted)? Do you want to argue that the dirt and solder splashes can come loose (IMHO not permitted), or are fixed (IMHO partly permitted)? Or do you want to argue that the wetting of some pads is below the required minimum, or just at it? Or that the solder balls are a defect or maybe allowed because of some exception?
Sometimes it is easier to just cut your losses and walk away.