That sort of loaned manpower isn't free, despite management's continued delusions that it is. Loaners have a cost, both up-front (onboarding, mentoring, reviews, etc) and on-going (lack of organic expertise in the new code remaining on the team, maintenance of suboptimal or inconsistent code, etc). But they're not the sorts of costs that show up well on balance sheets, so good luck convincing anyone that they exist.