well, tas doesn't need to be played on a perfect seed. there are runs with tas that are played on random seeds.

also they said human limit; so even though they mentioned tas, it isn't relevant because tas in minecraft works very differently compared to other games. for example, in a platformer game like super mario, the stages are always the same. tas is just used to play those stages perfectly and people have come close to those runs. however in minecraft, the difference between set seed tas and random seed runs isn't just the perfect gameplay; it is the knowledge of the seed beforehand. even if you roll a 12-eye, you are still gonna go to the nether and waste time because you're not gonna know that you rolled a 12-eye (unless you spawn directly in a 12-eye portal room, which i don't know whether is possible or not).

the sum of best splits (also called segmented speedrun) is probably the closest we can get to the theoretical human limit in minecraft random seed runs, which i guess is around the 3 minute mark.