One of the brothers was so happy upon knowing that you will be attending the conference that he left his wife while she was in labour. Is his action correct and is he sinful for leaving her?

Shaykh Muḥammad al-Waṣābī:

If her relatives can take care of her, or his relatives, female or male from behind a screen, and he left for her what she needs of money, then it is okay. Allah ﷻ said:

۞ وَتَعَاوَنُوا عَلَى الْبِرِّ وَالتَّقْوَىٰ ۖ

Cooperate with one another upon piety and righteousness.” (Q 5:4)

and this is a type of cooperating upon piety and righteousness. He has come to seek knowledge, to learn and then return – if Allah ﷻ wills – as a teacher for them. But if he left no one to care for her and has not left money that she is in need of, then he is a sinner. He must repent to Allah ﷻ and seek forgiveness.