"Those who were raksasas in previous ages, have taken birth as brahmanas in Kali-yuga to torment the physically weak saintly persons who are engaged in the culture of hearing about the Lord."
In other words, this verse shows that birth is no guarantee of pure spiritual pedigree in Kali-yuga, for even demons are born in the families of brahmanas. It is also interesting to note from this sloka that those demons in the guise of brahmanas obstruct the saintly devotees engaged in chanting the holy names of the Lord.
Prabhupada also mentions in this Bahagvatam purport 1.18.47. I am just copying and pasting.
if the question is raised why the brāhmaṇa community as a whole was made responsible for allowing Kali into the world affairs, the answer is given in theVarāhaPurāṇathat the demons who acted inimically toward the Personality of Godhead but were not killed by the Lord were allowed to take birth in the families of brāhmaṇas to take advantage of the age of Kali. The all-merciful Lord gave them a chance to have their births in the families of pious brāhmaṇas so that they could progress toward salvation. But the demons, instead of utilizing the good opportunity, misused the brahminical culture due to being puffed up by vanity in becoming brāhmaṇas. The typical example is the son of Śamīka Ṛṣi, and all the foolish sons of brāhmaṇas are warned hereby not to become as foolish as Śṛńgi and be always on guard against the demoniac qualities which they had in their previous births.