In general, if functioning properly, hydraulic tappets don't lose an appreciable amount of their "pump" from one start to the next, even over several days. Regardless, when they "pump up" - they never inflate enough to cause valves to stick open when they should be closed. Most, if not all MB engines are interference design - a stuck open valve is going to kiss the piston.

Of course, I suppose a lifter could potentially fail and cause a valve to float, but we're talking failure conditions, not inflation due to high cold-start oil pressure.

The problem with your car is fuel related, as evidenced by your solution of disabling the fuel pump to prevent additional fuel from being dumped into the system until the motor fires - this means there's already too much fuel there. Cutting off the pump still allows some fuel into the engine, as the injectors are going to open when they should, there just won't be much, if any, pressure behind the gas in the lines.

Any car, injected or carbureted needs an enriched fuel mixture to aid in cold startup. Cars with carburetors use a butterfly flap to reduce the volume of the air coming in, which correspondingly increases the air speed, which pulls more fuel through the venturis = richer mixture. Fuel injected cars solve the problem in several ways - some use an additional injector in the throttle body, some just increase the injector duration to provide more fuel.

Cars that exhibit hard-to-start/flooded behavior after a short start-then-stop cycle have some part of the cold start circuit confused about what is required of the system. When you start a cold engine, all of the heat is concentrated around the cylinders at the top of the block, just where the heads meet the block - the second area to heat up is the exhaust manifolds. When you run the motor briefly, that area gets nice and toasty very quickly, and then that heat slowly spreads to the rest of the engine after shutdown. Possibly when you restart it a short time later, the areas of the engine that benefit from enriched fuel during cold starts are actually warm enough to not need it, but the sensors that control the cold start cycle are still seeing a "cold" motor, as they get their readings from the coolant. The fuel injection computer calls for enrichment, which that actual combustion areas of the engine don't need - and you get a flooded condition.

This behavior, I wouldn't think, is normal - there's something wrong somewhere that's causing it.