It could be so...but the eastern Empire was woven of the same cloth, had the same lead and lasted for another 1,000 years.
It wasn’t so much lethargy, imho, it was complacency and a cultural softness. It was a citizenry that was fed but did not have to work. If they weren’t fed they would have burned the city down. The army became mercenary, not citizen. It shifted far beyond the urban centers where barbarians were paid to be nice, as it were...that was weakness manifest.
Eventually it simply became too much to manage...but to the point of the article: at the height of the peak lead spike was the best times of the empire.
I would say the same thing about us: during several lifetimes of lead paint and lead in other places, we managed to create unsurpassed inventions and a lifestyle unheard of in the world. Trains, boats planes and automobiles, went to the moon, cured infections...all while supposedly swimming in a hazardous lead environment.