Bret Devereaux isn't wrong. He's also not in the film business.
Ridley Scott thinks "acceptable" means he may at least ask a historian to suggest things. He won't give Russel Crowe a raygun, he may misuse ballista freely and reinterpret gladiator school freely. They didn't die usually? Pshaw.
"nitpick" is the kind of pejorative he'd use I think. I don't think Devereaux is nit-picking, the battle scene and a shitload of other stuff is about as a-historical as you can get without Kirk Douglas and Ray Harryhausen.
"The Duellists" which is Scott's movie of a Joseph Conrad story is beautiful, "Barry Lyndon" (by Stanley Kubrick) levels of attention to detail. I have little doubt Historians of Napoleonic era rip it to shreds. Harvey Keitel and Keith Carradine .. just wonderful.