If you read the entire article, it’s not nearly as bad as the excerpts. He quotes from both those who deny and those who insist on the reality of martyrdom.
Some actual facts. Roman persecution of Christians was not consistent or constant over the period between Christ and Constantine or over the entire empire. It was limited to episodic enforcement of the laws in various areas at various times. Usually the main victims were bishops and priests, not ordinary rank and file Christians.
Estimates are only that, of course, but the toll estimates vary from 10,000 to 100,000 for the entire period from 33 to 313. While a very large number, given the immense time span and area covered, this does not indicate any consistent attempt at genocide.
It is probable more Christians were martyred during the 1600s in Japan than under the Roman Empire. 37,000 were beheaded in one incident; the Romans had nothing like that.
Sadly, it is also true that a large multiple of those martyred by the Empire have been created since Constantine by other “Christians.”
I don’t think anybody believes that persecution is automatically equivalent to genocide or even attempted genocide.