Yeah I see "PPP" in the picture but nowhere is there an explanation of how they accounted and adjusted for inflation on a yearly basis. A link to the actual study would be a lot more informative. At any rate it doesn't address the moral concerns brought up in the article.
no mention of inflation in your link, only PPP. The article author also goes on to state that this isn't enough / as meaningful as you're making it out to be...
"And making sure everyone's making at least $1.25 a day isn't the end of the fight either. The world's median income is still only $3 to $4 a day. By comparison, the poverty line in the US for a family of four is $16.61 per person per day. Once under-$1.25-a-day poverty is eradicated, the world needs to set about eradicating under-$15-a-day poverty, which will be a substantially harder task."