Well you can define the word "theft" that way if you want, but I see a big difference between punching someone in the face and picking up an object, whatever words you use for it.
So you can't use the moral weight of the former to make responding to the latter with actual physical violence seem significantly more necessary to me than responding with physical violence to people who don't pay taxes.
I think it's perfectly appropriate to use violence to take back the object that you crafted and someone stole from you. I don't think it's appropriate to use violence to force someone to hand over an object they crafted and which they never agreed to cede to you.
So are you. Theft is not violence. If you walk into my house and take my valuables, at no point have you done anything violent.