It woudl be dubious of me to post the photos would'nt it..
Keeping your supply chain details quiet, is not being dubious.. Its a matter of loose lips sink ships..
There is nothing dubious about posting evidence to support your claim, or elaborating on details. Nobody has requested that you post confidential information on a public forum. My request is for, at least, the
type of details that are visible. Perhaps even pics with the details you are concerned with blocked out (replaced with a description of what was contained perhaps)?
You mention they clearly showed "the customers logos, details etc." but don't elaborate on what details were shown that could be confidential. Then you say the PCB was from SparkFun, whose products are mainly open-source hardware.
Give SparkFun a buzz and see if they're alright with it. They might appreciate you bringing this up especially if they expected this to be confidential.
You have been posting your own supply chain info (for PCBs at least) on several forums threads, so does seem odd to me that you attack them on this angle.
I get that they have annoyed you and welcome your feedback but if you go too far it does start to sound like sour grapes.
It appears the OP is annoyed at the way in which ALLPCB brags by carelessly sharing pictures of panels containing info about other customers. That is understandable but there is not enough info about what details were exposed. The customers may have given ALLPCB permission to divulge this too, but this hasn't been communicated clearly (typical of many Chinese manufacturers).
But until there is elaboration on what details were shared, it's difficult to say that these actions were negligent. What could be a trade secret, or even confidential, on a panel of SparkFun PCBs? Standards markings (eg. "UL-94V"), date/time/revision, some alignment holes, test points?