Shouldn´t the Amphibian have Start Latches ?

[Wothan]

IRL does the Caravan Amphibian have Start Latches or would that be optional ?

Start latches on Turboprops are normally set by kkeeping the Prop Lever forward, then move the Popwer lever into Beta and then Condition lever to Cut-Off.
This way, special Latches locks the Propeller blades in 0° Blade angle (Beta idle)

This is to prevent any thrust from the Propeller on startup.

To disenage the Latches, the Power lever is set to idle and the Propeller lever into Feather and then back to forward.

This is simulated on the SWS Kodiak 100 Amphibian.

[ErnieBall]

PT6's are free turbine engines. From what i know, only fixed shaft engines utilize prop locks for holding blades locked at flat pitch to alleviate the tremendous drag otherwise caused by the Feathered blades during start-up.

[Wothan]

Not true
I know that the Twin Otter Float and Amphibian have those (Also PT6 engines).
The SWS Kodiak 100 also feature these.

The reason is that if the props would startup feathered, once unfeatherd the "surge" would make the Aircraft start moving.
So You want to latch them at zero angle blade pitch during startup (which is opposite being feathered).