You make a good point. I'll grant you that.
OK so it seems we've narrowed down the possible scenarios of this battle. Now I feel we've determined that Revan is too smart fully attack Malachor V. He could infiltrate, but that's another matter. And as for Traya, she's too smart to engage Revan in open warfare.
So what's gonna happen? Traya is gonna stay at Malachor V for the most part. This gives us that prolonged war we've been talking about. With that in mind, I'll elaborate.
Let's look at what COULD happen in a prolonged war:
1. Traya wins due to her assassins unbalancing Revan's army and creating chaos. This is unlikely due to Revan leadership and overall charisma. I feel he could keep his men in check.
2. Traya and her army begin to starve and experience an extreme lack of supplies. Many things could happen here, but they all mean victory for Revan.
3. After a long time, Revan figures a way to infiltrate Malachor V. This could end in many ways, but it would likely spell victory for Revan.
Once again, I feel that the only way Traya wins is through a BIG mistake on Revan's part.
If Revan can keep his men in check that would restore an advantage to him. However, the "starve the enemy" startegy wouldn't work. It would work on her soldiers, but the Sith there would survive. The Dark Side would keep them alive. Once Revan feels that this strategy is not working, he has to attack Malachor. Either with his army, or solo. Either way, the Dark energies of Malachor will be his undoing.
These energies are what corrupted him in the first place, and will do so once again. Malachor is a powerful Nexus of Dark Side energies, and these energies would corrupt many of Revan's Jedi and turn them against him. This would lead to Revan's forces fighting amongst themselves while the Sith grow stronger. Eventually, Revan would stand with but a few followers. The Dark energies would corrupt or destroy many of his followers.
So now Revan has only a few Jedi and soldiers with him to enter the Trayus Academy. An Academy filled with Sith Lords. If Revan managed to make it through, he would be the only survivor of his troupe. He would enter the Trayus Core and face Darth Traya, who would break him. Empowered by the Trayus Core and the power of Malachor, Revan would either win barely or be corrupted and join Traya. Either way, Revan would be corrupted by the Dark Side.