ASA Rule Book, Rule 8 Batter-Runner and Runner, Section 3
F. Failure of a PRECEDING runner to touch a base or to legally tag up on a caught fly ball,
and who is declared out, does not affect the status of a SUCCEEDING runner who touches the bases in proper order. If the failure to touch a base in regular order or to legally tag up on a caught fly ball
is the third out of the inning, no SUCCEEDING runner may score a run.
G. No runner may return to touch a missed base or one left too soon
after a following runner has scored or one he leaves the field of play.
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So by
G R2 could not touch home plate once BR3 scored. Effectively, R2 "missed" home plate.
By
F, since the appeal on R2 for failing to touch home plate was the third out of the inning, the succeeding runner (BR3) could not score a run.
Therefore, the ruling of a tied score & extra innings was made correctly.