My understanding of reproductive labor is limited, but it isn't just birth and childrearing, it's also stuff like housekeeping which enables wage laborers to work. Both expansion and maintenance of labor. Although queer people engage in that sort of thing (we all do to some extent) more than lumpen are economically productive, the reason I made the comparison is numbers. Lumpen are only a small fraction of society and capitalism tends to maintain a constant reserve army of labor, in contrast to the ever-increasing share of proletarians. Artisans would have been a less loaded example, a small class of laborers that doesn't have much power (except that nobody thinks artisans will lead the revolution). My problem is the authors don't really explain why the fraction of queer people might expand until they are doing enough reproductive labor to take the reins. They just handwave "gender's process of decay".