Is it conceivable that Ibn Abbas would assert the distortion of the Quran through the addition he mentions in His saying: ﴿ فَمَا اسْتَمْتَعْتُمْ بِهِ مِنْهُنَّ ﴾ [An-Nisa: 24], where he recites it as "إلى أجل" (for a period)?

The tradition referred to does not involve a distortion of the Qur’an; rather, it is an interpretation or an abrogated reading, similar to the abrogation of the ruling permitting mut'ah (temporary marriage). Ibn Abbas initially ruled permissible because he was unaware of its abrogation. He later retracted his statement after learning of its abrogation and prohibition. The Prophet, peace and blessings be upon him, forbade mut'ah with women on the day of Khaybar, and this prohibition is what the people of knowledge have agreed upon.