The issue of interbreeding was discussed in the other thread (linked to in the OP). But basically, the OOA tree model fails to account for the fact that while we carry recent African-origin genetic material we also carry genes of recent non-African origin, which is and always has been the MH position.
The two models have never been mutually exclusive. If about 5% of our genomes are from crossbreeding and the other 95% from our African ancestors, then the MH model explains 5% of our genome and the OOA model explains 95% of our genome.
It's a bit like the "argument" between gradualism and punctuated equilibria. You can have both.