"The six-month return to competition rule is standard across most sports for athletes returning to international competition. And necessary," Ings said on Twitter.
"If Jarryd Hayne had been playing in WADA-compliant sport he would have grounds to reduce the 6 months.
"But NFL is (performance enhancing drugs) badlands. No chance."
Ings first made headlines as a 22-year-old tennis umpire who took on John McEnroe.
He was ASADA's inaugural chief executive and chairman following its creation in 2006 to replace the Australian Sports Drug Agency.
But the federal government replaced Ings in 2010 amidst talk of mistrust and in-fighting within ASADA ranks.
Hayne and World Rugby are yet to respond to Ings' tweets.
Fiji's coach Ben Ryan also says that Hayne's place in the 12-man Olympic squad is not guaranteed.
"I have no promises he is going to make the 12, but we will see how he goes," Ryan told the World Rugby website.
"He will then come into Fijian camp for the Olympic period. It is a huge challenge for Jarryd but if he gets into the squad it is only going to be on form, because he is a blinding rugby player. If he doesn't make it, is just shows how good this Fijian sevens side is."