Uncut hair is good exegesis of
1 Cor. 11. as has already been explained. You may have come to different conclusions on the interpretation of those verses, but to say uncut hair is not biblical; that is unproven by the arguments made against it. I personally don't think that uncut hair in itself may necessarily be a salvation issue, but I do think it is the correct rendering of
1 Cor 11.
I think another big question is would people obey if they ever got cut or uncut hair as a revelation of the scripture. Many people refuse to comply with passages of scripture out of inconvenience. I think it then becomes an issue of the heart.