Read the executive summary available via the link above.
"Their assistance with household tasks and childcare are seen among the most important contributions and also constitute the main (indirect) economic benefits, as it allows hosts, especially immigrant women, to seek or increase employment or education to improve economic outcomes."
Visiting, foreign grandparents assisting with childcare is encouraged. I don't know why people spread these theories that lack humanity, go against human nature, community and valuing support over autonomy, struggle and individualism. I've seen this "illegal work" comparison used all over this site within the context of visitor grandparents.
Grandparents being grandparents is not gainful employment. It is a village.