Of course the government should meet with rebels. You know what happens when you don't meet with them? Trouble continues on a large scale and the tensions continue to mount. You want to come together and at least try to come to an agreement and find some sort of common ground.
I see no reason why the Thai government should not, at the very least, have some sort of a cordial meeting with the rebels in that country. Diplomacy is never a bad idea, especially if in the act of doing can prevent any kind of an armed conflict, for sure.
I do not see any good reason as to why the Thai government should waste its time meeting with rebels. The rebels have already shown that they have absolutely no interest in making peace or in working something out, so why waste the time or energy engaging them in talks.
Even though the situation in Thai seems awful, I do not believe that meeting with rebels will solve the crisis. Anytime a terrorist organization wants to help, it benefits them more than the people who are being repressed. I believe they need to try to solve the many issues themselves or they will be in a worse situation after the problem has been resolved.