Why did Rudra fight against the devatas in the Tārakāmaya war?

Question

One of the famous wars between the Devatas and Dānavas is the Tārakāmaya war. This war took place when the Soma, the moon god abducted Tāra, the wife of Bṛhaspati. devatas took the side of Bṛhaspati whereas dānavas fought for Soma due to their enmity towards devatas. It is mentioned in various purāṇas. Similarly it is mentioned in Brahma Purāṇa also.

What interesting is that Rudra fought against devatas in the war. Following is an excerpt of the chapter from Brahma Purana in which the birth of Soma is described.

स याच्यमानो देवैश्च तथा देवर्षिभिर्मुहुः |
नैव व्यसर्जयत्तारां तस्माऐ त्र्प्रम्गिरसे तदा ||

Although repeatedly requested by Devas and celestial sages, he(soma) did not handover Tārā to Angiras.

उशना तस्य जग्राह पार्ष्णिमन्गिरसस्तदा |
रुद्रश्च पार्ष्णि जग्राह गृहीत्वाजगवं धनुः || 9.21

तेन ब्रह्मशिरो नाम परमास्त्रं महात्मना |
उद्दिश्य देवानुत्स्रुष्टं येनैषं नाशितं यशः || 9.22

Ushanas attacked Angiras from the rear. Taking his bow Ajagava, Rudra did the same. A miraculous missile named Brahmishiras was launched by that noble deity Rudra against Devas. Thereby their fame was destroyed.

• Why did Rudra fight against the devas, sages and support moon god?
• Is the reason mentioned in any other purāṇa besides Brahma Purāṇa?

Answer 1

Seems to be a difference of interpretation. Unable to find "Rudra" word in the verse 9.22. Suppose a synonym or sandhi of Rudra is present in 9.22, even then it's likely that the translation might be wrong. As Rudra mostly support Deva-s. It's clarified in other Purana.

According to Vishnu Purana Chapter VI, Rudra didn't fight against Deva-s, but supported them.

The son of Atri was Soma (the moon), whom Brahmá installed as the sovereign of planets, of Brahmans, and of the stars. ... he became arrogant and licentious, and carried off Tárá, the wife of Vrihaspati, the preceptor of the gods. n vain Vrihaspati sought to recover his bride; in vain Brahmá commanded, and the holy sages remonstrated; Soma refused to relinquish her. Uśanas, out of enmity to Vrihaspati, took part with Soma. Rudra, who had studied under Angiras, the father of Vrihaspati, befriended his fellow-student. In consequence of Uśanas, their preceptor, joining Soma, Jambha, Kujambha, and all the Daityas, Dánavas, and other foes of the gods, came also to his assistance; whilst Indra and all the gods were the allies of Vrihaspati.

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This is clearer in further story, which suggests that Brahma intervened and stopped Rudra & others to fight for Soma. Soma was asked to return Tara, however she was already pregnant with Soma's child!

In this the gods, led by Rudra, hurled their missiles on the enemy; and the Daityas with equal determination assailed the gods. Earth, shaken to her centre by the struggle between such foes, had recourse to Brahmá for protection; on which he interposed, and commanding Uśanas with the demons and Rudra with the deities to desist from strife, compelled Soma to restore Tárá to her husband. Finding that she was pregnant, Vrihaspati desired her no longer to retain her burden; ... both Vrihaspati and Soma, fascinated by his beauty, claimed him as their child. The gods, in order to settle the dispute, appealed to Tárá; but she was ashamed, and would make no answer. ... Brahmá again interfered, and pacified the child; and then, addressing Tárá, said, "Tell me, daughter, is this the child of Vrihaspati, or of Soma?" "Of Soma," said Tárá, blushing.

_{Note: Answer is corrected as per suggested in comments.}