Kirk can make his eye disappear. Since he can turn into Nick but flaws. But it has no eyes (at times like someone said his style can change) but how he can change is style is by shapeshifting so yeah. that's one theory I have yeah my theory is basically that his shapeshifting can be like- no eyes/eye who knows. But it could be obvious that that might be Canon but I don't know

Another theory.

Junior can somehow come back to life but from the dead. Or can be revived and then died again from Kirk. cause of those tapes and stuff.