Well, both were first round picks. Anderson has reinvented himself as a reliever and is knocking on the door. That's an easy selection for a bullpen weak team to see if he can stick.
Stewart has increased his K rate by about 25% and dropped his walk rate to go with it. Considering his biggest knock was his K rate (which is very respectable in AAA this season), someone might. You may be right that these guys are marginal 40 man adds. We don't see them either, so who knows. I'd think both are risks to go personally.
Anderson wasn't a first round pick. Maybe you are thinking of Tyler Jay? He will be eligible for Rule 5 this winter too.
Anderson was a 32nd round pick from Brainerd who initially had to go to indy ball.
Stewart, his K rate increased in his 3rd year at AA, but just a tick above league average. It is back down to well below average at AAA. He's giving up more hits than ever, although he is still getting grounders. Seems like he would most likely be selected for conversion to relief duty, and in that case, I am not sure he is in all that different of a position from last year.