When you are the direct, contracted, IT support for a company then you do have responsibilities. You might be considered responsible for timely delivery of patches - a fair argument in court I think. Mitigations might involve helpdesk logs as well as contracts.
well_done: Your tone comes across as BOFH. I'm possibly a simple PHB who owns an electric cattle prod that is wired up to the mains (three phase) but I prefer to get sign off for a project via work committed and not threat done.