Is anti-Brahminism in accordance with Hinduism and its scriptures? Is it a sin or is it glorified?
Anti-Brahminism is a sin and against the rules of Hindu scripture.
The various Dharma Shastras prescribe various punishments for different types of abuse hurled at Brahmanas.
On [verbally] abusing a Brāhmaṇa the Kṣatriya should be fined one hundred; and the Vaiśya one hundred and fifty; or two hundred; the Śūdra however deserves immolation.-(267)
"For the Śūdra ‘immolation,’—in the form of beating, cutting off the tongue, actual death, and so forth, to be adjusted in accordance, with the exact nature of the abuse."
If a once-born person [Shudra and below] insults a twice-born one with gross abuse, he should suffer the cutting off of his tongue; as he is of low origin.—(270)
If he mentions the name and caste of these men with scorn, a burning iron nail ten inches long shall be thrust into his mouth.—(271)
If through arrogance, he teaches brāhmaṇas their duty, the king shall pour heated oil into his mouth and ears.—(272)
Other Dharma Shastras regarding verbal abuse:
Gautama (12. 1, 8, 10-13).—‘A Śūdra who intentionally reviles twice-born men, by criminal abuse, or criminally assaults them with blows, shall be deprived of the limb with which he has offended.
Yājñavalkya (2.206.207).—‘The fine is half for reviling one lower than one’s self, double, for reviling women and superior persons; thus shall the fine be inflicted in accordance with the superiority or inferiority of the castes concerned.
Viṣṇu (5.23, 33-35-38).—‘If the Śūdra uses abusive language, his tongue shall be cut off;
Āpastamba (2.27.14).—‘The tongue of a Śūdra who speaks evil of a virtuous person, belonging to one of the first three castes, shall be cut out.’
Bṛhaspāti (20.6-11).—The Śūdra shall be compelled to pay the fine of the first amercement for abusing a Vaiśya; the middle amercement for abusing a Kṣatriya 5 and the highest amercement for abusing a Brāhmaṇa.’
With whatever limb the low-born man hurts a superior person, every such limb of his shall be cut off; this is the teaching of Manu.—(279)
If he raises his hand or a stick, he should have his hand cut off; if he strikes in anger with the foot, his foot shall be cut off.—(280)
If, out of arrogance, he spits, the king should have his two lips cut off; if he urinates, then his penis; and if he breaks wind, his anus.—(282) If he catches hold of the hair, the king shall unhesitatingly have his hands out off; also if he lays hold of the feet, the beard, the neck, or the scrotum.—(283)
Should politicians support Brahmins or be against them? According to scriptures, the politicians are obligated to support Brahmins:
Manu 9.313 - Even when fallen in the deepest distress, the king shall not provoke the Brāhmaṇas; for if provoked, they would ruin him, along with his army and conveyances.
Manu 9.317 - Learned or unlearned, the Brāhmaṇa is a great divinity; just as consecrated or unconsecrated, the fire is a great divinity.
Manu 9.319 - Similarly even though they betake themselves to all sorts of undesirable acts, yet Brāhmaṇas should be honoured in every way; for they are the greatest divinity.
Manu 9.322 - The Kṣatriya flourishes not without the Brāhmaṇa; the Brāhmaṇa prospers not without the Kṣatriya; the Brāhmaṇa and the Kṣatriya, when united, prosper here as also in the other world.
Gautama (11.14).—‘It is declared in the Veda—“Kṣatriyas, who are assisted by Brāhmaṇas, prosper and do not fall into distress.”’
Vaśiṣṭha (19.4).—‘It is declared in the Veda—“A realm where a Brāhmaṇa is appointed domestic priest prospers.”’
But this doesn't mean that Brahmanas shouldn't be punished, for the commentator Medhatithi says:
When they betake themselves to forbidden acts, they shall be dealt and punished according to law, gently, and not attacked with force, in the manner of other castes.
Nārada (18.12).—‘On account of their dignity and sanctity, it is not permitted to either advise or rebuke a King or a Brāhmaṇa, unless they swerve from the path of duty.’
By "advise" it actually means "criticize," since kings have advisers.