It doesn't matter if poverty might be used as an election topic. If economy is a possible election topic, do you stop publishing economic statistics?
It's a farcical situation, but this needs to be put in context.
To start with, poverty isn't an simple thing to quantify. There isn't a universally accepted definition. The government have their own definitions, which they use to inform policies such as the "universal asignacion por hijo". Their definitions of poverty are relevant to their goals and their policies. These goals and policies are not shared by opposition parties or hostile media. They might as well have asked him "how many people in Argentina aren't doing so well" and then acted outraged when he said he didn't know.
If they had asked him "how many people qualify as indigente, based on your quantifiable definition of indigencia" he might have been able to answer. But he would need to explain what indigencia is, and how and why they quantify it in the way they do. And even if he tried to explain what the data indicated, the press would report that "Axel still thinks you all live on 6 pesos a day". Not surprised he chose to keep his mouth shut, even though he looks feeble for doing so.
The "6 pesos a day" debacle was a sad day for journalism, and a damning indictment of the state of the media in this country. A story that should have been debunked as bogus within a couple of news cycles ran, and ran, and ran. Eventually even the international media began parroting local press screeching points. Unfortunately smug stories about loony latinos, barmy argies and their silly economies and policies are popular in the international press. Case studies on how effective hostile media blocs are when they align to disseminate propaganda aren't a top reporting priority, strangely enough.
The government's work in reducing poverty has won it votes, both from the people who have benefitted (who the opposition dismiss as being "bought") and the people who do not benefit directly but ideologically agree with it. Their vote is still in play.
Publishing poverty statistics proved politically disastrous, so it appears that the government simply stopped publishing them. Which is ridiculous. It's also a ridiculous situation to be in - feeling unable to publish national data because it will be misrepresented, used against you and will cost you political support. But this is ultimately what happens when you have weak institutions, a weak press, and weak government.