basically this DIP is telling you this
1. your house (which falls under general development) must be at least 4.0m above the Singapore Height Datum.
2. if your house is already 4.0m above the Singapore Height Datum, then your house must be at least 300mm above the adjacent ground/road level. this 300mm is the level required to prevent water from flowing from the ground/road into your property
PUB will give your the MPL (minimum platform level) which your house needs to be built. the MPL is the level where the 1st storey must be location at or above.
so now if they tell you your house must be 1m above road level, it means your existing ground/road is only at 3.0m above the Singapore Height Datum. so your 1st storey must be at 1m above road level. anything below this 1m can be considered as a basement if you choose to build a basement. building height of 12m will be computed from this MPL.
there is no way you can escape this clause since PUB is unlikely to grant you clearance if your design is below the MPL. if PUB don't give you clearance, URA will not give you PP or WP and BCA won't give you permit so you can't do anything.
edit: above the table already has the clause "The Minimum Platform Level for development on the selected area shall not be lower than the highest level shown in the table". so it's take whichever level is highest.
the other clause of owner accepting risk is only applicable if there are site constraints. you need to read the DIP in the entire context and not pick and choose which ones you want. quote from my own DIP, "If the minimum platform cannot be complied with due to site constraints or other technical reasons, the owner/developer shall make the following endorsement on the building plan: “The Owner/Developer has given due consideration to PUB’s advice on the minimum platform level and is aware
that the lower existing/proposed platform level may subject the development to flood risks”."