He has aerials that boost recovery, a boost that he can use consecutively, and the ability to put out aerials with this move, which gives him options for recovering high too. He can also shoot his laser if he is recovering high.
Non-linear in the sense that he has options. No other character can use a long horizontal boost into a long vertical boost. This is all relative to the rest of the cast, mind you. I can't think of one character that has better options in terms of recovery, or that can recover such a large distance (excluding puff).
God? Is that you?
That is amazing, I might actually have to learn how to customize my PM for this.
EDIT: HEY DRINKING FOOD LINES CAN BE OFFSET AT DIFFERENT ANGLES. DON'T TRY TO PASS THAT **** BY ME BECAUSE I'M HIGH SCHOOL EDUCATED MOTHER****ER
His dair stall is nothing special because his drifting is so bad. Bair does not even serve a purpose for his recovery.
Things ROB does not have in his recovery:
Getting anything back when hit
Getting more than one boost back on edge grab
Good hitbox coverage (except nair which is good but only if you are recovering high) (fair is prone to trade and only covers directly in front of him
A sweetspot below the edge
Small hurtbox that are hard to hit
His best way to stall is actually up-b fairs, not dairs, but if he trades or gets hit at all after he's expended a boost or two he is usually dead. You have to choose in between an airdodge and a third boost, too. Lots of characters have ways to cover or limit his options forcing him to guess how to safely come onstage. His recovery is good when coming in high because everybody's is, but his coming in high is good because you can cover yourself with nair. Thing is, in order to recover high, you usually have to expend a boost or two to get there, so if the opponent is smart and goes for a trade you die.
Additionally, that's all assuming you can recover high, because sometimes you can't sometimes your opponent is sheik or many other characters who can send you off at a low angle. Sometimes your opponent can jump as high as you can recover and trace your fall back down, cover all your options for delayed boosts back on, then covering your direct side-b to ledge.
ROB's recovery is definitely above average, even for somebody that knows the matchup. But it's not godly, not even top tier, that distinction definitely applies to characters like DDD (who really IS almost immune to gimps thanks to up-b distance), jiggs, samus, m2, peach, all of whom have a recovery even after hit (multiple times!) and don't expend as much of their recovery distance as onstage tools.