Hopefully I'm not too hazy on the details but here's the basic gist of it all:

Trump sipped the Fiji water during his first press conference back from Asia, having just flown over the Fiji islands on the way back (including Wakaya, which is/was owned by Clare Bronfman, high ranking NXIVM member, NXIVM used this island in some capacity).

Some people think that Trump was deliberately sending a message with not only the brand of bottled water but also the way he chose to sip it (or pretend to sip it, as I contend): he held the bottle as one wearing handcuffs would hold it. And the whole thing was just very deliberate, like he wanted people to take note of it.

A few months later, the leader of NXIVM, Keith Raniere, would be arrested. And a few months after that, Clare Bronfman would also be arrested.

So the message would be "Justice is coming to these people". Bronfman would end up pleading guilty and Raniere would be found guilty.

Edit: the guy interviewing David Rodriguez having Fiji water I think was just coincidence.