You will probably be just fine as long as long as the bed is well-mulched. You will probably get some freeze-browning on the leaves but that's not going to kill the plant. Here in New England I've grown various alliums that had leaves of 3" to over a foot tall by the time real freezing weather hit, and with a good leaf mulch they all survived through to spring and grew very well.

I did the same thing in MN last year as well. Had 6" to 8" tops before we really got a good freeze last year.

No issues whatsoever. 100% germination and they all made it through the winter just fine. Over 100 bulbs.

softneck and hardneck too - they were both great. I mulched about 4" to 5" of leaves and they were easily through the top of that.