When Chambers returned to the sport yes he was booed. He was booed at the national champs, he was even booed (by far less people of course!) at the British League. Then as time passed, people became more accepting. When he competes now, people cheer. However he wasn't really a contender at the top as other sprinters had stepped up (CJ Ujah and James Dasaolou). Even in 2012 a lot of people had mixed feelings about him.
This is from an athlete that only cheated once, and showed remorse unlike Gatlin.
Of course, I fully agree the crowd should have booed Makhloufi in 2012, Ayana after the joke of a performance on the weekend and others. However Gatlin is going to be the only top contender who has twice failed a drugs test, whilst others remain under a cloud of suspicion.