Put the effort into the other bushcraft skills and interests, as well as become knowledgeable on your local laws. Don't make it an argument, but try to get your dad to explain his point of view. Keeping in mind that adults often hold opinions that they have not thought about at all, or come from their own very painful pasts, which they don't really want to revisit. There is a lot of stuff you can do without a knife, and as much as a lot of people don't think about it, basic day to day skills of the modern era are just our version of the life skills that were needed a hundred years ago that we now call bushcraft. Being able to fix a tap and being able to make a water filter are in some ways a similar style or type of skill. My being able to write a grocery list and my ability to food plan for a couple weeks at a time or even create a larger food supply that can be cooked in adverse conditions are just extensions of each other. I had the advantage of growing up in the wilderness with parents who understood that those skills might actually save my life. Where I live now I know heaps of people who spent as much time in swimming lessons as I did in the woods because people here spend a lot of time in pools and the ocean, and the smart ones know how to be ready for an incident in that environment. It's also basic car repair/care, and those modern things. I know that it's the bushcraft that you are interested and that's cool, but you can use all those other areas to show you are responsible, which will help. Also, there is no bushcraft without the bush, if there is a volunteer group in your area that maintains trails or plants trees (you'd be amazed at how many urban tree planting groups there are) that again is another avenue to learn. And yeah, worst comes to it, you become an adult and you do your own thing, but if you spend the next three years getting a heap of skills that don't "need" a knife you will far more able to problem solve. Add to that, you should do a first aid course anyway if you haven't already, and other tools like saws and hatchets have their own risks, but might not have the same perception, and you can do a lot with a saw.
But the thing to keep in mind is that parents make decisions and then spend the rest of their lives wondering if they did the right thing. So ask, but don't be shocked if you get the answer when you are 25, just don't let that be a thorn in the relationship, overall it's not worth a fight.
