No, I think this falls entirely in line with the Japanese idea of accepting responsibility through suicide. Sasai was Obokata's mentor, he was instrumental in getting her papers published, and now he's caused a massive loss of face for not just himself, but the generally very well regarded institution he works for (Riken).

Don't get me wrong, I'm not saying he should have committed suicide, I'm just saying that I can entirely see why he would have considered it a valid option to discharge his guilt.