All of their sediment filters are absolute, thats all they will sell based on experience.
Personally I'm anal about my water quality and since you have no idea what that 5 TDS is made up of you might want to toss it.
Even before DI resin is exhausted, it starts releasing weakly ionized substances such as phosphates, silicates and nitrates. These may or may not register well on a TDS meter so I never use water that shows any TDS as it could likely be worse that you would suspect. The resin is setting there collecting all these contaminants until it reaches its full load. At that point it is tired and starts releasing some back in to the treated water, remember RO/DI water is agressive and trying to get back to its natural "dirty" state so is pulling things back into solution to try and equalize itself electrically.