The Third Man Fallacy

Presumably according to anti-Penal Substitutionary Atonement groups it would be unjust for God to punish a third party therefore He could not do that. However it would be unjust for God to not punish sins but these same people believe He could do that.

God Gave His Son- Jn.3:16-17, Rom.5:8, 8:32 2 Cor.5:19-21, 1 Jn.4:9-10, 19…etc.
Christ Gave Himself- 1 Tim.2:6, Tit.2:14, Gal.1:4, 2:20, Jn.10:11…etc.
• Jesus Christ is God
• The Man Christ Jesus
• Penal Substitutionary Atonement is be...