Thanks for asking, people hardly ask for eachothers opinions and get mad right away.
My thoughts:
between each string 21,/24/1121 you can poke. yes lao can use d3 on you but the problem here is he cant make use of that advantage because standing 2 doesnt hit mid, so even if he is at +10 you can still poke him out of his standing 2 pressure and you will be back into your advantage again. Your d4 is +16 on hit, so you have the option to get a block string hitconfirmable into net, or the command grab, both are deadly options. basically a lao player hitting you with a d3 doesnt really mean anything.
PL knows this and thats why he spins, so its not random, he is trying to blow up your pokes. However the lao player can do 21,21212 instead of 21,21 so if you try to poke after the second 21 you will get hit by the 21212 hitconfirm into spin, because you expected the string to finish at just 21. However I doubt you have seen anyone use 21212 this way, because I am probably the only lao that uses this currently, haven't seen jr or PL do this at all.
also 2121 is hard to punish on block for a lot of characters but you can always get your block string and you have that command grab to use because kung lao is stuck in that position so he has to block your strings or tech your grab.
also if the lao player tries to follow up his d3 on hit with b33spin, just cross him over,the hitbox on b33 is horrible so it will whiff.