TNA are idiots because they're bringing him back, again, after he's been in trouble multiple times over, and fired, from one company for being in trouble over and over again with drugs.
Giving the guy a second chance after the first time is one thing, continuing to bring him in and push him knowing that he's completely unreliable and a moron only serves to prove how stupid the people running TNA are.
Does WWE look the other way? You bet they do. They all do. But you note that WWE has also fired people, or suspended people even while they're the champion, for getting into trouble over drugs.
They stripped RVD of the World Title, and suspended him when he couldn't stay off them. They let Angle out of his contract to seek help for his, and he instead went to TNA and only allowed his problems to get worse. They got rid of Jeff Hardy cause he couldn't stay out of trouble and off drugs.
TNA, instead, continues to allow Angle to comeback, but at least this time they're sufficiently wasting his talent with this stupid angle with Jarrett, and they're going to continue to let Angle work.
Not only that but now they're adding an even bigger addict, and headcase, into the mix of things by bringing in Chyna. So, yeah, while all companies loko the other way it would appear TNA is doing all they can to set the record for looking the other way.