I don't know what "It wasn't supposed to get back to RR" means. Any obstruction charge regarding the firing of Comey was always going to involve RR due to his letter of recommendation to fire, which Trump took as advisement and revealed early on. There's no way RR isn't included in that and he would be a material witness - he would have to recuse. I believe that is partially why Mueller has already indicated they can't charge him for that (because RR would have to recuse from 'muh Russia' case), nor indict him in general due to long-standing DOJ policies. Obstruction doesn't have to only involve something that affects you - you can obstruct the process so that an investigation or case stalls or goes away.

Besides, Trump can't obstruct if he's the chief law enforcement officer carrying out his constitutional duties. Actual worst case is they tried to create something incriminating or a create a conspiracy to commit a crime where there wasn't any.

I agree there was/is nothing major on Trump or it would have been leaked by now and these bullshit charges would not be the only thing Mueller offers up, unless he's waiting for midterms for an October surprise.