So, by the same token, when the tree (very soon) starts to outgrow the pot, if you prune it it will then put up suckers, too. Vendors might tend to tell you it's all right so they can sell you a tree, don't forget.
Jmho, Quakies are not a good candidate for growing in a pot. I'd plant them in the ground then just cut off the suckers as they come up. If you want a solitary tree, you should buy something better suited.
We planted a row of transplants that we dug up on a relative's property in Utah. Only about half of them made it, but the rest have now made a pretty little grove. We let the suckers grow, of course because we wanted a clump of smaller trees, not just a few big ones. I would think to contain the suckers, some sort of concrete edging might do the trick. Ours did not get out of hand in the 5 years our son lived in that house.