Grenade is ticking! (Far Cry 5)

This is done for convenience in case of delay the throw no more, life is not ticking

Time-delay fuses with mechanical clockwork device a long time ago not to use in explosive devices and even a makeshift Assembly. But for movies and games is a kind of Canon.
And hand grenades and even more so never any was not applied.
Besides, to hold a grenade with activated fuse is stupidity. First, it is dangerous, the fuse may burn out much faster or much slower than the time at which it is targeted. In the second, grenades in General it is not designed. After pulling out checks, lever escapement fuse remains fixed, while the hand does not release the grenade.