Post-freeze citrus question

I'm pretty sure I know the answer, but I'd love for someone more experience with citrus trees to weigh in. I have a young Meyer lemon tree (it was probably about 2 years old when I bought it 2 years ago) that did not do well in the freeze. The card from the nursery (Urban Roots, RIP) says its cold hardiness is 30F. New growth is finally emerging, but it's all close to the bottom. I'm assuming I've lost the graft and that the growth I'm seeing is from the root stock--so, probably no reason to keep it, right? If I'm wrong, I'll happily nurture it back to health, but if I'm right, I can plant something else in that sunny spot. TIA!