Now, these claims by the author can be very easily refuted. Because all Shastras have condemned all kinds of non-vaginal sex.
From Baudhayana Dharma Sutras 3.7.7:
A man who considers himself to be in some way impure offering with the
Kusmanda formulas.
A man who ejaculates his semen in any place other than the vagina* becomes equal to a thief, equal to a murderer of a Brahmin (A 1.19.15
n.). He is freed from any sin short of urdering a Brahmin (TA
2.8.1–3).’ 4 Now, a man who has ejaculated his semen in any place other than the vagina except in sleep, or even a blameless man who
wants to purify himself, should get the hair of his head, beard, and
body shaved and his nails clipped on a new-moon or a full moon day.
Following the rules laid down for a student, he observes a vow for a
year, for a month, or for twenty-four, twelve, six, or three days. He
should not eat meat, engage in sex, or sit on anything above the
floor, and recoil from uttering an untruth
This rules out all kinds of sexual conduct other than the usual one.
Further verses from 4.1.22 of the same text:
One who does not have sex with his wife during her season (A 2.1.17
n.), and one who has sex with her outside her season, as also one
who deposits his semen in a place other than the vagina (B 3.7.2
n.)––they all incur the same guilt
and from 4.2.10
When someone, moreover, has consumed unfit food or forbidden drink or
food, or performed a sinister rite, whether it is done deliberately or
not, and when someone deposits his semen in a S´u¯dra woman or in a
place other than the vagina (B
3.7.2 n.), he becomes purified by bathing while reciting the Ablinga and Va¯runi verses.
Similarly, from the Gautama Smriti 25.5:
When someone cheats, slanders, does forbidden things, eats forbidden
foods; when someone ejaculates his semen in a S´u¯dra woman or in any
place other than the vagina (B 3.7.2 n.); or when someone performs
witchcraft even intentionally––he should bathe, reciting the Ablinga
or Va¯runi formulas, or other purificatory texts.
And, the most severe punishment I have seen being mentioned for anal sex in any of the Hindu scriptures is death punishment mentioned by Lord Shiva in Mahanirvana Tantram :
The wicked man who enjoys the wife of one of a higher caste should be
heavily fined, and kept on a diet of grains for three months (40). And
if the woman is a wilful party, she should be punished as above
mentioned. If the wife is the victim of a rape, then she should be
separated from, but maintained by, her husband (41). A wife, whether
married according to Brahma or Shaiva form, should in all cases be
renounced if she has gone with another even if it be only once, and
then whether of her own desire or against it (42). Those who have
intercourse with public women, or with cows or other animals, should,
O Deveshi! be purified by being kept on a diet of grains for three
nights (43).
The punishment of those wicked men who have unnatural intercourse with a woman is death; this is the injunction of Shambhu (44)
Mahanirvana Tantram Chapter 11.
