Car fixed, $2500 for VVT and while they had engine apart put in lower chain guards (include diagnosed ($500.) $3k total)

Is it true that this rattle at cold start is first sign of bad vvt and if you continue to drive would be catastrophic engine failure? By belief, and that of my mechanic is the failing VVT was present before sale of car to me. Can anyone confirm this chain of symptoms and then engine failure? See below for explanation of car trouble.

*sequence of events;
Very next day after purchasing car, rattle at overnight startup. Next morning same rattle at startup but only let car run for about 5 min. shut off and came back after 2 hours, no rattle. Seems that as soon as vvt is oil pressured charged even for only few minutes then shut down, several hours later a restart with no rattle? Just want your thoughts on this vvt situation, thank you for your time.