The Buddha was enlightened, not sexist

Ven. Anālayo Bhikkhu (Buddhist monk) in a letter to the nun Ayya Tathāloka

(Isharak) In the fifth year after his enlightenment, the Buddha spent the rainy season in Kutagarasala. It is the abbey where he most frequently stayed while visiting the great city of Vaishali. It was here that his stepmother, Mahapajapati Gotami, was ordained as the first Buddhist nun, creating the Bhikkhuni Sangha. (To visit: 1upindia.com)

Gender Discrimination and the Pali Canon

...In the case of the attitude towards women, we find contradictory positions and thus a lack of consistency in the Pāli canon [the oldest extant redaction of the Buddha's teachings].

One example is the account of the founding of the Order of Nuns.⁴ According to the "Great Final Nirvana Discourse" (Mahāparinibbāna Sutta), soon after his awakening the Buddha proclaimed that he would not pass away until he had nun disciples who are wise and learned.⁵

From this it would follow that right from the outset he wanted and intended to have an Order of Nuns. This impression is further supported by a closer perusal of the Pāli canon, which shows recurrent references to the importance of having four assemblies of disciples (monks and nuns and male and female lay followers) and to the significant contribution made by nuns to the prosperity and success of the Buddha's dispensation.

These passages stand in contrast to the impression created by the account of the foundation of the Order of Nuns, which reads as if the Buddha did not want to allow women to go forth.⁶

A comparative study of this account in the different collections of Disciplinary Rules (Vinayas), mainly extant in Chinese, shows clear signs of later additions and thus makes it probable that it does not accurately reflect the Buddha's attitude.

Another example would be a pair of discourses in the Collection of Numerical Discourses (Aṅguttara-nikāya) that compare women to black snakes -- as both are dirty, smelly, and betray friends, and so on.⁷

Would it be reasonable and coherent for an awakened teacher to make such derogatory remarks about women?

That enlightened teacher, according to other discourses, had nun-disciples that had reached full awakening and thus total freedom from any defilement,⁸ who according to the same discourse collection proclaimed various nuns and lay women as outstanding in qualities like deep concentration and profound wisdom,⁹ and who apparently placed such trust in women that he (in a twin monastic regulation found in all Vinayas) sanctioned acting on a trustworthy laywoman's report about a monk's breach of the rules?¹⁰

The comparison of women to snakes recurs in two parallel versions -- one in the Tibetan Vinaya, where a similar remark is headed by the qualification "some" (i.e., "some women are..."¹¹) and another in a late text in Uighur [a language in China], where this remark is not made by the Buddha, but rather by some Sakyan youths.¹² More plus footnotes

• The first all Sri Lankan nun's great almsgiving
• Buddhist nuns of Burma (allmyanmar.com)