At least the Gladiators that lost!

Correction twenty out of twenty-two gladiators that died in one particular place ate mostly but not exclusively plants.

Two other did not follow said died because they didn't come from the same area.

That's a drastically different conclusion

How do we know they didn't follow the diet because they didn't come from the same area?

Maybe they were special otherwise? Super stars? I.e. this may well be coincidence. At a sample size of two any conclusion is a tad hard to support.

There is overwhelming evidence for meat being consumed rarely in most western cultures until very recently. Excavations of food pits mostly.[1]

The link I posted is just one example.

[1] My brother is an archeologist. I take his word for this.

Well I hope that his evidence is stronger than your overstatement of the link you posted.