From his Behance page: "Half a year's worth of work, weeks of waiting on end because they couldn't find the fingers at the end of their arms and in the end they try to screw me over by ignoring the invoices. "
That a pretty aggressive play in words. I suspect if he is really looking for "justice" he'd gain a lot more support in exposing the entire situation, not just some pretty screen shots and shouting about unpaid invoices.
I for one am genuinely interested in learning more about this, both sides preferably.
My guess is that this was not the method of first resort.
The trouble I have thus far is the information is insufficient to make a fair determination of who is right and who is wrong. People are having knee-jerk reactions and harassing the gym without fully knowing the story, and yes, that is truly unfortunate.
If you are ready to close the case on this one simply by a developer claiming he wasn't paid, well, you may wish to rethink your logic with that one.
Has anyone vouched for the credibility of this developer? Have more details surfaced as to the extent of the invoice dispute? Without those answers it's unfounded to hold anything against this gym solely based on the developers claims that he wasn't paid.