No, it was while he was in symbiosis, for about 5 pages, with The Trespasser. Literally the Life Force of the universe, same thing as Phoenix. Except Jean actually IS the Phoenix, and the Phoenix is Jean. Hal only had help, with an added side effect.
Also they say at the end of the story that eventually Nekron will win. Which of course he will, he is as powerful as God (the DCU character) and all life is basically an accident. Nekron is basically the DCU explanation of entropy, his victory is inevitable.
The Phoenix/Jean, however, cannot die, is the life force of the Marvel Universe, exists across all of space-time and can create and can destroy matter as she pleases. So, is, in short, omnipotent. All Hal did was prevent the early death of the universe, leaving the Vanishing Point to try and help everyone. Which eventually they do.