I haven't seen anyone say that a Plaid handles better than a Taycan. I know that I certainly haven't. That said, a Plaid doesn't handle dramatically worse than a Taycan as you seem to be suggesting. From my perspective, they're both big, fat pigs that are made to go around corners by having big, sticky tires, but for going fast on the Nurburgring, that works. You don't really need great transitional handling, but your car has to be able to stick and be stable, especially in high speed turns. It's mostly down to grip, tire and aerodynamic, and not banging on the bumpstops while having as low a center of gravity as possible. In this regard, I doubt that there is any significant difference between the Taycan and the Plaid. Bump taking ability is useful for being able to run over a few curbs and on the Carousel, but it's not too important for overall lap times. The car also needs to be able to slow down repeatedly, which the Track Package on the Plaid does seem to accomplish.It's not exactly the minimum engineering effort. However, it will be engineering effort in the area that Tesla has proven they can use to sell cars. Which is acceleration, particularly 0-60. And maybe something a bit flashy like bigger brakes that take no engineering just asking a supplier (see M3P brakes).
The fact that people then say that a Model S Plaid handles better than a Taycan because it has a faster 'ring time then tells you that this method of just focusing on acceleration works, and is a very, very efficent way for engineering effort to turn into sales and brand perception, as acceleration is the easiest thing to add to an EV.
The fact that the Taycan and Plaid have such similar 'Ring times with such dissimilar acceleration and mass tells you just how much better the Taycan handles. The Turbo S is 6.0 seconds 0-100MPH and the Plaid is 4.2 seconds, and 150 MPH is 14.2 vs 9.6 seconds. Yet over 7 minutes of driving, the Plaid is only 7 seconds faster. That's only a couple 100-150 MPH sprints difference yet the 'Ring is full tens of those.
How does this all apply to the M3P highland? Yeah, not very likely that it's going to try and benchmark the BMW M3 CSL in everything. If it hits it at 0-60 and maybe 0-100, Tesla will probably consider themselves done. The interior and chassis is not their goal, because consumers have told them they don't care.
There aren't 10s of 100-150 MPH sprints on the ring; you're engaging in a bit of hyperbole there. Also, as Nabush points out, the Plaid was thermally limited during its record lap. How much, we can't really tell for sure, but it was obvious in a number of places. Even without the thermal limitation, I don't think the Plaid would have been able to turn a 7:07, but it certainly would have been quite a few seconds faster.
From the article about the new Taycan GT, the rumors are that it has 3 motors and 1000 HP, so basically matching the Plaid for HP. It also looks like it has wider tires and a fair bit of aero work, which will make a difference as well, but it sounds like the biggest advance for the Taycan is no thermal limiting, so it can actually use that power for the entire lap.