Are you using tonegym to become a better musician? If so go ahead, it will help you associate the intervals in your ear with their place on the fretboard! After a while you won't need to use your guitar and your ear will hear them and you'll instantly know which note to play on the guitar if you play it back.

It's more than that: It's a SIN (if you're into that nomenclature).😄😜 Just kidding! There are older posts that talk about this matter way deeply, but I'll give you my opinion.

Who do you think you're cheating by using an instrument to help you through first stages of learning? Yourself? I don't think using any tool available in order to learn or improve your ears' skills will hurt you... Other ToneGym members? I'm sure everyone does trainings, plays games and learn at his/her own pace, comes here with a diversity of starting points and, of course, use whatever he/she has at hand to learn and improve regardless of what the rest are doing or what scores they get.