Not sure where you’re working, but your senior devs are quite misinformed.
Every layoff I’ve witnessed sliced quite a bit off the top because they’re the most expensive. Absolutely no regard for who was maintaining what legacy projects, often leading to months of setbacks while the remaining engineering staff tries to understand a critical yet unsexy tool or service that no one else was willing to touch.
Having “special” projects is in no way a form of job security.
If your business is operating like this it’s not sustainable. You need 10 developers for every project so the senior developers can complain about meetings instead of exposing themselves to code review. That helps there supposed knowledge.
Every layoff I’ve witnessed sliced quite a bit off the top because they’re the most expensive. Absolutely no regard for who was maintaining what legacy projects, often leading to months of setbacks while the remaining engineering staff tries to understand a critical yet unsexy tool or service that no one else was willing to touch.
Having “special” projects is in no way a form of job security.