It isn't that implausible that LTT's leadership was disputed, after many years of terrible war without a victory in sight and since the Light forces became thrown back again. One should also remember that LTT was probably very arrogant, so that he might angered other important politicians. That then eventually many in the Hall rather allied with Latra, apparently a charismatic leader and good speaker, also doesn't seem that far-fetched to me.

Anyway, that seems to be RJ's explanation and in the end we have to buy it.