ARPA-H has a mandate beyond aging, according to the FAQ [0], everything from cancer research to healthcare access. While, according to the article, in the most recent funding bill for the ARPA-H "...the Senate has recommended funding geroscience research..." and "... urged [the ARPA-H] to prioritize two areas of geroscience research: biomarkers and epigenetic reprogramming.", that is a long way from actually allocating the entire budget of ARPA-H [the mentioned $1.5B] towards age-reversal technology. No money may end up being allocated towards age-reversal technology, and if some is, it's only a going to be a portion of a diversified portfolio of research the agency will fund.
[0] https://www.whitehouse.gov/wp-content/uploads/2021/09/092921...