He also went back and said that they got that wrong, so it's not really your best piece of evidence.
If you want some straight up math, here goes.
The highest damage MAR rotation is BB>SE>BB>SE>Frac, or 2780 (630 + 610 + 630 + 610 + 300) potency over 13 GCDs, which is 213.85 potency per GCD. The only additional potency you're gonna get is from auto-attacks, which is 83.33, and Brutal Swing, which is 50 potency every 30 seconds for 4.17 potency per GCD. Totaled up, that gives you 301.35 potency per GCD on average (218.02 from special attacks; 83.33 from auto-attacks; this will be important later on).
The high damage DRG rotation is insanely long thanks to the CDs on a lot of unequal durations, so I'm not going to list it out and instead use straight up math: HS is 1 GCD out of every 8, CT is 3 GCDs out of every 12, Phleb is 1 GCD out of every 8, Frac is 1 out of every 8, and the rest is made up of Full Thrust. All of this adds up to 216.67 potency per GCD (1/8 * 170 + 3/12 * (760 / 3) + 1/8 * 290 + 1/8 * 220 + 9/24 * (650 / 3)). DRG also gets, off-GCD, Leg Sweep for 130 potency every 20 seconds for 16.25 potency per GCD, Jump for 200 (w/ 50% extra from Power Surge on half) every 40 seconds for 15.625 potency per GCD, and Spineshatter Dive for 170 every 90 seconds for 4.72 potency per GCD. The auto-crit from Life Surge is basically a free crit on Full Thrust, or 150 extra, every minute for 6.25 potency per GCD. Tack on the 83.33 for auto-attack and you get 342.8 potency per GCD (216.67 + 83.33 + 16.25 + 15.625 + 4.72 + 6.25).
For multipliers, MAR would get 20% from Maim, 11.1% (1/.9 actually) from Storm's Eye, 2.375% from Internal Release, 5% from Blood for Blood and 2.22% from Raging Strikes. Berserk adds 2.667% to special attacks and 8.89% to auto-attacks. DRG gets 10% from Heavy Thrust, 11.1% (1/.9 actually) from Disembowel, 2.375% from Internal Release, and 7.5% from Blood for Blood.
Put there together and we get these formulas:
MAR: (218.02 * 1.02667 + 83.33 * 1.0889) * 1.2 / .9 * 1.02375 * 1.05 * 1.022 = 460.8 potency per GCD
DRG: 342.8 * 1.1 / .9 * 1.02375 * 1.075 = 461.1 potency per GCD
Furthermore, compound this with the fact that DRG gets the STR traits, MAR doesn't get the job stat bonuses, and that the MAR gear is severely lacking on secondary DPS stats and DRG pulls away pretty quickly.
So, yeah. You wanted full on theorycrafting and I gave it to you: MAR isn't going to do more damage than a DRG and, at best, will likely get upwards of 85% of a DRG/LNC's.