MapleGuru
Seedling
What does the lowest chop look like? Can you take a photo showing it from that side? If the callus is still increasing I would think you might be OK, especially if you do go ahead an chop somewhere above to encourage more shoots...or graft something onto the right side. If the callus has stalled then maybe you have a problem. From this angle it looks like the callus hasn't really covered up much of the original chop site but that just may be the perspective.
I've got trees in my growing bed that look like this and I haven't seen any evidence of the trunk dying back below the first chop (not yet, anyhow).
Yes, the callous is increasing. I think it will be ok, but that doesn't mean Im right. Each time I have scored the callous(2xs this year), it recovers and continues to grow.