The wiki say some pokemon can't learn tm's?

Is it true? And if it is, will their movesets be updated to include tm’s in the future?

I’m guessing you are referring to pokemon that got wiki pages after 1.2. They can learn TMs, but people didn’t take the time to figure out every TM they could learn and update it. By default, when no TMs that can be learned are put into the TM learnset, the wiki says it can’t learn any TMs at all. They will get updated in the future eventually though.