So a brigade is what, 4000 men ?
Defensive role is okay. But still it will make us party of the conflict and we will no longer be unbiased observer. I also don't understand why KSA will need a brigade from PA ? I mean they are more then capable of protecting their own soil and they have been doing so since years now (houthis didn't just came today). Still, I agree to the request but with following conditions.
1. All the expense of that brigade is paid from KSA armed forces budget.
2. And we choose the place where we want to station those soldiers. Some Arab guy dictating our soldiers and running a circus won't be okay.
3. Every soldier will get secondary pay, obviously. As they also pay secondary salary when on space missions to other countries so yah.
4. And yes we want deals on investments. No loans, no grants. Invest here.
I think I can come up with a conspiracy theory on that. Maybe Saudis somehow wants to drag us in the conflict. We send brigade for defensive roles and suddenly it get huge attacks from houthis "allegedly". Killing hundreds of our soldier. Kaboom. Now you are fighting Yemen houthis as well as Iran.