You couldn't say it better.
Plus just to add one more thing, when usually source don't accept this anonymous testing two reason come up in my mind: they are not sure of their product or they don't have the money to pay for anonymous testing. And there is nothing worse then a source short on money... Because shit hits the fan fast in this business and if you don't have the money to fix problems, pay back ppl or reship... Well we know how it went in the past.
Plus unless you test ALL your raws every time you buy a new shipment, testing once mean nothing.
I want this source to be good, we all want but we aren't naive kids like when we started. We have seen (I have seen less then the other but was enough trust me) so many sources gone to shit, scam ppl, get a good reputation just to rack up money later and when ppl start noticing that Te quality went to shit... Was to late. They were gone. New name, new identity.