Probably a scribal error for מֵחֲבֵירוֹ.
This is the reading of Yalqut Shim‘oni Isaiah §481. The Venice-Leyden version “R. Abbahu” is certainly corrupt.
Text of the Rome manuscript; the sentence is missing in the Leyden ms. and the Venice print.
In the Biblical text עַתָּה “now”.
The text here is that of the Yerushalmi from the Genizah and, partially, from the Rome manuscript; the Leyden/Venice text is shortened by omission of the words in parenthesis.
Text of the Rome ms., in place of דרבי in the Venice print.
Reading of the Rome manuscript; “Rebbi Eleazar ben” is missing from the Venice text but R. Yannai is later than R. Eleazar ben R. Antigonos.
This is the reading in the Rome manuscript and the Genizah fragments. The Venice print has “Rebbi Isaac” which is impossible because Rebbi Isaac is older than Rebbi Simon and because later the Talmud text refers to Rebbi Phineas.