Where is your proof? You're just stating it's a mode just BECAUSE he went through rin unintentionally. There's other explanations, I am not saying that what I say I am saying is 100% true but, for now you can't say that it's an actual fact either.
^^ Exactly you have point it was never stated as phasing ability work... but rise our heads, Fourth Databook is incomming and let s hope it clear more things then it create another problems.
Phasing could work like that:
1) auto turn on and turn off basing on physical contact with Obito's body
2) Obito having to turn on it and turn off, but his body would react automatically with turn on and turn off phasing
3) Obito has to focus and decide if phasing work and each part of body has to phase.
Here I want to add my thoughts about it.
Well I agree with OP about how phasing ability work, because it seems once he activate MS The phasing ability seems to be enabling/turning on every time when something comes in contact with Obito's body.
Yes, he can uses both Kamui warp at the same time, well he can ever use any attack except Kamui warp while phasing as proved already. Although if phasing work as I described then it is close to impossible to prove that Obito is phasing while attacking because phasing turn on and turn off automatically when he comes in contact with something and when something looses contact with his body.
Anyway, I believe Obito can NOT use Kamui snipe while phasing and I have good proofs for that:
1. The manga has never shown neither Obito or Kakashi using Kamui snipe while phasing, It was never stated that he can as well.
"Not shown != can not do it until it will be shownn" accepted by everyone simple law about feats of characters.
2. However there is another harder proof which completly show neither Obito or Kakashi can kamui snipe while phasing. The proof lays in Kishi creating specifically conditions/situations when certain character could proves certain combo is possible to use and can be use as feat.
In Obito's case there was no such case, sadly. However arguably Obito's charka powered DMS Kakashi with Rikudou chakra had two situations in which he could display such feat, and Kishi made him not to either restrict/nerf him or simply show "Kamui user can not do it"
a) First opportunity was when Kakashi was phasing through ash bone while approaching flying at him Kaguya at full speed. Kakashi could easily uses Kamui snipe if he could.
These excusses as She has even better S/T and She can regenerate. First has nothing to with it, unless you finally admit Kaguya was enter Kamui dimenssion, while second one makes not difference as nothing stopped Kaguya from regenerate from Kamui Raikiri which was just new show off as fan service because Kamui snipe would do the same thing(it could rip her arm and even more the arm along with BZ could be warped to other dimenssion - better result)
b) When Kakashi was falling down and used Kamui snipe Kishi would easily hype even more Kamui users by making either Kaguya or BZ shooting ash bone and make it phasing through Kakashi while he was warping her Space time Portal from which ash bone was emerging to hit Naruto.
Even If logic could say that making just Eye stay tangible while rest of body phasing would be enough then it still doesn't make it true as manga has shown it can not be done.
RESULT:
Kamui user can not use long range warp while phasing.
