During Wednesday's episode of The Jump on ESPN (h/t ESPN's Rachel Nichols), Pierce dismissed Bynum's comeback attempt as nothing.
"I have a better chance of probably coming back than Andrew Bynum," Pierce said. "He's been out of the game four years. This is only my second year out of the game."
Per Shams Charania of The Athletic, the Los Angeles Lakers gave Bynum permission to use their facilities to work out as he attempts a comeback.
A first-round pick by the Lakers in 2005, Bynum won two NBA titles with the team in 2008-09 and 2009-10.
Injuries were a problem for Bynum during his professional tenure. The New Jersey native missed at least six games in eight of his nine seasons, including the entire 2012-13 campaign.
Despite making just 26 appearances in 2013-14, Bynum performed well in a limited role with 8.7 points and 5.6 rebounds per game. That was his final season in the NBA to this point.
Bynum, 30, was also a member of the Philadelphia 76ers, Cleveland Cavaliers and Indiana Pacers.
Pierce, who will turn 41 on Oct. 13, last played for the Los Angeles Clippers during the 2016-17 season. He averaged 3.2 points per game and shot 40 percent from the field.