I haven't read through AN's argument for why he doesn't rate Grace as an all time great, but I 100% agree with the fact that we shouldn't be rating him as an all time great cricketer.
Grace dominated his era, that's undisputable, however the cricket he played back then is totally different to the game we see in the last 100 years, it's basically another sport.
I'm of the firm belief that if you bring Sir Braddles up in todays day and age he will still dominate the game because the skills are transferable, however with Grace it is actually impossible to say he would be good, never mind as dominant as he was against his peers because he played a different game against players which were frankly not serious.
I mean he could be an ATG, as much as Usain Bolt could have been an ATG if he played cricket, or Albert Einstein could have been. We have no way of knowing, but when in doubt you tend to say no because the burden has to be on the proving he is an ATG player.
Grace's impact on cricket as a sport is close to unrivaled, however that doesn't make him an all time great cricketer. Grace's aura and persona and standing in the game is what blinds people. He has legendary stories about him, he's almost a fictional character. That's better for the game than an ATG player, but if we're judging on skills, you can't hand on heart have him as one of the best of all time.