Didn't you read the rules? It is clearly written on their website that they have the right to request a verification, which will also allow for AML and KYC verification. It is also clearly written there: "The ImExchanger service will not enter into business relations with a user suspected of or directly related to money laundering or with a person whose funds were obtained as a result of illegal activity."
Let's assume the user did not know but they completed the KYC because they had to complete it.
But did you know what is the current situation? According to him, the exchanger marked the order as paid, but this user did not receive the funds. Don't you think it is something bad? Even if they do not have the intention to scam, do you think it is right to mark an order as paid even if the user does not complete the KYC? Moreover, he said that Bestchange removed his feedback from their website and this user was unable to leave feedback anymore. This does not look good.