He was saying that Swipe threat is greater than Lacerate application threat, not the Lacerate DoT threat. Instead of refreshing it constantly, throwing in Swipe and waiting to refreshing the Lacerate stack generates more TPS.
And I really wouldn't use PP for a proof of threat generation, especially as the 3rd tank. Threat will have been long since established in phase 1 by the MT, since there isn't usually people on full-time DPS duty on the boss. I'll just assume that your PP example was to show that your Lacerate bleed damage wasn't dropping, but with how often you apply it, there should be no question.
“Society is endangered not by the great profligacy of a few, but by the laxity of morals amongst all.”
“It's not an endlessly expanding list of rights — the 'right' to education, the 'right' to health care, the 'right' to food and housing. That's not freedom, that's dependency. Those aren't rights, those are the rations of slavery — hay and a barn for human cattle.”
― Alexis de Tocqueville