I looked it up in a couple of other versions and the meaning should be that if they DO NOT overcome this base clinging thirst that their sorrows will flourish. Obviously this makes much more sense, since overcoming base clinging thirst should reduce suffering, right?! So correct syntax would be:
Whomsoever in this world
is overcome by this base clinging thirst,
his sorrows flourish
like well-watered biira.na grass
Now there is no (or little chance) of misinterpreting the contents. The other translation is slightly ambivalent. Just picking at nits!
With the eye of wisdom we discover a lot of anger in us, any amount of jealousy, resentment, ignorance, desire - mountains of emotion whose existence we would never have suspected in ourselves... We recognize that most of the faults we perceive in others are only the mirror of our own negativity, the reflection of our own disturbed feelings... At the same time, we relieve the world around us of the burden of our own negative judgements."
Gendun Rinpoche Heart Advice from a Mahamudra Master