Everything still falls down to being scam. From your explanation you only understood one part of what I said earlier on. For sure, asking for payment in advance may seem to be a scam from the service renders but subsequently the client may fail to send the payment after they have recovered his/her wallet.
Asking for payment upfront is not a sign of scam but the problem is that, majority that are scamming people for this reason are mostly using this pattern so that they can run away with clients money without a trace. Some well known wallet recovery services may asked for partial payment upfront without sounding like it's a means of scamming their clients.
There are different brands that are into fund retrieval on lost wallets and due to their advancement and work ethics, they may choose to ask for payment before they start work in order to fund the the necessary procedures that is required to retrieve funds in clients wallet.
you are right asking for payment upfront is not a sign of scam, there are companies and organisations out there that usually ask for payment upfront from their client's before rendering their services to them, although most people use that strategy as a means to scam people, especially their client's no doubt, but that's by the way. Let me now put this question directly to the keychainX representative, what are you people's policy when it comes settlement, do you guys receive payment from your client's before rendering your service or after rendering the service?