What the parent comment meant is that business owners love the illegal immigration status quo so they can rip workers off overtime and wages because those workers can't complain to the government.
Your analysis is simply off. The side pushing for worker and immigrant rights are not saying "please keep immigrants here so we can exploit them more".
transcriptase was likely referring more to thrawa8387336's comment than to thinkingtoilet's comment. thrawa8387336's comment says "There would be turbo-inflation" as justification for continuing to exploit workers.
Your analysis is simply off. The side pushing for worker and immigrant rights are not saying "please keep immigrants here so we can exploit them more".