Grant Hill back in the day was really fukking nice bro. Maybe as good as LeBron, KD, Kobe, or Harden are now brodie. Probably not better than any of them, but they're all on the same tier. Let's not act like this is an outrageous take.
Also from the way old heads tell it, hand checking was still widely used back then and was used as a crutch by defenders, making them look a lot better than they were. MJ defensively would be Tony Allen today with more shotblocking. I think Pippen's defense today would be a lot better than MJ's, and he'd also probably win at least one Defensive Player of The Year Award.
I don't think Gilbert was putting them down as defenders. I'm sure he still thinks they'd make multiple All-Defensive teams each. It's just that in MJ and Pippen's runs they weren't facing Wade, Kobe, Harden, KD, LeBron, PG, Melo, Giannis, Kawhi, Devin Booker, Bradley Beal, Donovan Mitchell, DeMar DeRozan and CJ McCollum every 2nd game. Let's not forget all the Point Guards I didn't list, that MJ and Pip would inevitably have to cover every few games.