User blog comment:Skeith9/Heroic Spirits Speculation/@comment-25951993-20160125134241/@comment-25951993-20160125150812

Methuselah is from  the  freaking   Genesis Era and A ncient Pre-Flood Earth. According to the biblical stories there were tons of people who grow to trmendous heights during that time.

Besides there are plenty of other people in the Type-Moon universe who dwarf other people including him.