Well, in theory... Labyrinth is about half walls, so you can get about 5 * 200 = 1000 piety just by worshiping Binlor (assuming of course that you do not get any of his wall-spending boons, i.e. basically wasting all the piety except for the Stone Soup boon). For the monsters, Dracul can give up to 4 Piety per non-undead kill, and then 1-7 Piety per blood pool drank, depending on level of sanguine. Since there were only a couple of zombies today, that could mean another 120 piety from kills, maybe another 100-150 from Sangune (B2P lets you keep drinking), and then all those health potions are worth 5 piety apiece, plus the HALPMEH and CYDSTEPP each worth another 10 apiece. Another 100+ Piety. Plus 2 desecrations. So, in theory, getting 1400+ should have been feasible (potentially a bit more if things are juggled more optimally, i.e. more stacks of Sanguine, etc.).
PISORF - with Rock Heart - can cost as low as 3 mana per wall destroyed. But for 200 walls, that's still 600 mana, which assumes spending pretty much all blackspace - and probably a considerable also from the level-ups and B2P - on nothing but knocking monsters thru walls.
Now, in practice, the JJ prep assumes he started in JJ, which means some blackspace wasted for less efficient piety generation, and since we know where Binlor was, it could have been quite late to find him. Furthermore, not starting in Binlor means no PISORF, and ENDISWAL costs 5 mana even with the refund...
So I'd say... technically should possible, but still quite a feat, and probably would require luck and/or prior knowledge of the map? Especially in 19 1/2 mins.