from older petrol cars ?
their turbos can run hotter than diesels , if I remember right a lean mixture in turbo petrol can lead to very high combustion temps, so the risk of it still being hot on shutdown is higher , I think a turbo timer just keeps the engine running for a given time to let cool down at idle speed, or perhaps temperature controlled?
unless you blast full throttle for a long time and then park up and switch off, its a bit pointless on a diesel.
as soon as you take your foot off the throttle to coast or idle the turbo cools down very quickly, as coasting/engine breaking injects no fuel just air is nicely cooling it already.
so if you've coasted under little throttle to where your parking I couldn't see turbo being hot enough to cause damage or cook the oil .
if you can wait a few seconds at idle all the better,
also the turbos don't want the engine reved just before turning off either as this will spin up the turbo to high speed then the oil pressure will drop when engine stops but it will continue it will continue to spin in a dry bearing and add to wear.
as an example of turbo temperature I run an egt gauge middle one in this vid 200c to 1200c
cruising around waiting to go full throttle not even showing on gauge below 200c
after a very hard pull wot through the gears reaching near 800c but see how quick it drops when throttle released.