As a team lead I would not except this kind of toxic gate keeper mentality. A single person with such a bus factor is a huge problem to a teams/projects (or God

As a team lead I would not except this kind of toxic gate keeper mentality. A single person with such a bus factor is a huge problem to a teams/projects (or God forbid departments) success. Discuss and frame it in terms of worries for business continuity with your line manager. If that does not click, consider it a red flag.