Oh, now I went ahead and read TFA. It's all complicated and confusing.
The current thinking is indeed that viruses are an offshoot of 'modern' life (modern being sometime after the archea). These critters, because they contain gene sequences that seem to predate the prokaryote - eukaryote split and because we know that bacteria just love to transfer genetic information 'horizontally' - that is by tossing bits of DNA and RNA around so some unrelated organism can incorporate it into their genetic apparatus as opposed to simply eating it - that it may be that these big viruses started sometime after the RNA hypothesis took hold and created the first self replicating organisms. Or at least helped those first 'organisms' diverge and multiply.
At least it's a testable hypothesis. Once you have sequenced a number of the big virus genes and compare them you would presumably get an idea how old they are.
It would seem that even if this mechanism held, the critters would have had a long time to morph into another ecological niche so it would be hard to pin down what their function was (if any) at the beginning of life. But perhaps the Central Dogma is barking up the wrong tree after all.