"My yavam does not desire to invest for his brother a name in Israel": R. Yehudah says: It is written here "name," and elsewhere (in connection with the daughters of Tzelafchad, Bamidbar 27:4) "name." Just as "name" there refers to seed, so, "name" here — to exclude (from chalitzah) a castrate, who, even if he wanted to perpetuate a "name" for his brother, could not.
"in Israel": and not among converts — whence it was ruled: Two brothers, converts, whose conception was not in holiness and whose birth was in holiness, are exempt from chalitzah and from yibum, it being written "in Israel," and not among converts.