See the verse given below:
If a Sudra uses abusive language or physical violence against twice-born people, the part of his body used
for the crime should be chopped off.
If he has sex with an Arya woman, his penis should be cut off and all his property confiscated;
if the woman had a guardian, then, in addition to the above, he shall be executed. 4.
And if he listens in on a vedic recitation, his ears shall be filled
with molten tin or lac; if he repeats it, his tongue shall be cut off;
if he commits it to memory, his body shall be split asunder. If, while
he is occupying a seat, lying on a bed, speaking, or walking on the
road, he seeks to be their equal, he should be beaten
Gautama Smriti 11.31.
So, the persons or Achryas who justify the execution of such orders, do so based on the simple fact that "there are Hindu scriptures that have such injunctions".
Acharyas are persons, who are well versed in the scriptures (Srutis, Smritis etc). They won't say anything that is not found in scriptures or that is in contradiction with what's being stated in the scriptures. So, what more or different can you expect from them?
If you want the real essence of Hinduism and it's scriptures, then you have to listen to what the Yogis, Sadhus have to say. They know far more than what is revealed in the scriptures. Or get initiated yourself and start your own investigation.