From the objective point of view, yes save scumming is cheating, but when you analyse it further it becomes murkier. You can refer to it as a scratch card, there are loads of wins which only give you the money back that you used to buy it with. This is essentially the same as the scumming, you buy 4 scratch cards, and all 4 give you the money you spent back, so you can go and buy more. Save scumming gives you the money back and places you at square one again, you regained what you spent, but have nothing to show for it. So you try again, hoping for a different outcome, only this time you buy the 4 scratch cards and 3 give you the money back, but one gives you a bigger win. This one is the triple roll you were going for, so you keep it and move on to try something new.
However, things get even murkier when people are scumming for shiny and pure rolls, since they are not going for the brand favoured ability triple. This is where it tilts the scales onto the cheating side of it. You are resetting your money/snails until you get a 1/4492 roll in like 10 or less "real" rolls (the ones that you used on that scum). This can become unfair when people start compiling builds that are technically impossible or extremely unlikely, since they can create a playstyle and role in a match that shouldn't be possible for the weapon in question.
Then again you have to consider the chance that people get these rolls purely by chance, and just imagine now that save scumming wasn't possible at all. How would you feel if you could never get natural rolls without 50+ rerolls on a piece of gear, yet here people are who get the natural triple after buying the gear (I have had this with the Strapping Reds, White Tee and Varsity Jacket) or re-rolled a piece of gear once and got a shiny or pure (I got triple QR on the Squid Hair Clip, and triple Swim Speed on the Shirt & Tie, both in 1 reroll)? It becomes very dubious and would fragment the player base with those getting slight advantages by having organised gear whilst others are getting screwed by RNG constantly. Sure, abilities aren't everything, but having things stacked and planned out to the point of maximising your efficiency and performance with a weapon can still have a significant impact on the outcome of a match, even if only slightly.
Based on how many people scum, and how easy and accessible it is to do, save scumming is not cheating in my eyes. You have to rely on the game giving you the roll you desire, which is completely RNG-dependant and has no reflection on the skill level of the player. Yes, the dictionary definition of the word makes save scumming cheating, but when you think about the masses who do it, and how it effectively allows everyone to be on a level playing field (except the more casual players who won't really go for all slots and the like). It isn't exactly harming people, and it isn't having a major impact on the matches or tourneys, so I wouldn't bother worrying about it. I don't see the point of looking down on save scummers, unless they deliberately do it to inflate their rank past their skill level, because abilities are so trivial and so small in their impact on matches, that it isn't a big deal. People will always have differing views on this, but at the end of the day, "If you can beat them, join them", because you can't beat their gear rolls unless you get extremely lucky.