If the whole product you're selling is just a thin wrapper around GPL code, why not simply sell the GPL code or GPL the wrapper? Surely the wrapper would be trivial for a competitor to replicate so the reason you're able to make money from it must be something else like other services you provide with it, or just the value of you having chosen and distributed that particular GPL program.
It was more of a thought experiment to show that a process boundary isn’t likely to be some sort of perfect defence, than a real example of how someone might operate.
