Apart from the horrible style and lack of nuance, it's simply not true. To reply in the same style: who pays for proprietary software, often can demand changes. With OSS, the user is in no position to do so at all.
There is of course nuance here, since large companies with many end users do not listen to their paying customers, and OSS developers can be responsive, but I don't feel particularly kind to someone who uses false and nonsensical premises to make a political point.
> the proprietary program's developer is tempted to design the program to mistreat its users
I mean ...