The NCAA statisticians manual states the following:

ASSISTED TACKLE: If two defensive players contribute equally to the
stopping of a ball carrier, credit both players with an assisted tackle, but
give neither a solo tackle.
NOTE: In a situation in which there is not a solo tackle, there should
not be more than two assists credited except in rare instances. In other
words, on any given play one of the following may be credited: (1) one
solo tackle, or (2) two assisted tackles. Only in the rarest of cases would
more than two assisted tackles be credited.

The manual states that there may be more than 2 assisted tackles in rare circumstances, so we need to account for it. Its at the digression of the operator. We agree that the 3rd tackle should not be used, but it needs to be there to be in compliance with NCAA guidelines.