I imagine this might fall under the mosaic theory (that non-insiders are able to undertake original research to correlate a wide variety of individually non-material data to form an opinion about a security). As far as I know, such actions (by non-insiders) do not fall afoul of insider trading prohibitions. Otherwise, how would stock analysis work?

Whether a card processor's handling of financial transaction flow would be viewed as non-insider is something that I don't know. I can make reasonable arguments either way.