I suspect this practice is a bit disingenuous of the bootcamps, a way to pad their “successfully employed” rates while keeping labor costs low. But it is hard for me to fault the candidates for putting those experiences in their resume. They need that money to keep their job searches going, and recruiters are always biasing against gaps on the resume.
If you’re being paid by them for any reason, put it on your resume. (And if you’re not…move it to the education section, where it belongs.)