I'm not sure about this, personally I'd say that grenade raiding would be perfectly fine if the persons base looks like a base, etc boarded up windows, barricades everywhere etc which would make me think that they are armed and ready to be raided.
I'd also say that in the case of the specific AR that it would be 2.5, as from what I see from the video there were no defenses or any sign of an actual base such as boarded up windows and barricades, but I can't really tell that for sure without further information.
I'd also take into consideration that you were acting aggressively in OOC, as if you were being disrespectful or maybe going as far as what could be considered harassing the person, then raided their base which had very little to suggest that it was a proper base that was actually being defended and you ran in and grenaded the person, it would seem much more like a targeted RDM rather than just an accident because you were raiding someone as you normally would. But once again I don't really have enough information to know if this was the case.