At this point of time it is only a local conflict, uprising of an oppressed group against the Yemini government. They have not launched any offense against the KSA and even in that case, Saudis should defend their country by themselves and not us (or anyone else for that matter). All we can do is to take the responsibility of the defense of the holy cities. Houthis are not our enemies nor are they something like the TTP/ISIS etc.
Besides, when our troops were fighting in East Pakistan or now against the TTP scum, who sent their troops to fight along our side? Were Saudis not aware that our resources are stretching thin? Could they not have helped us with their fighter jets? our financed us for much needed gunship helos? Are we the contractors of supporting Saudis, especially when they are carrying out preemptive strikes that is nothing but an aggression?