Of course you can use the UCC to defend yourself against these drug charges. I am sure that both your attorney and the court will be both suprised and amazed at your incredible grasp of law in discovering this 'drug loophole'.
By the way, do you even know what the cited UCC subsection says????
"§ 1-207. Performance or Acceptance Under Reservation of Rights.
(1) A party who with explicit reservation of rights performs or promises performance or assents to performance in a manner demanded or offered by the other party does not thereby prejudice the rights reserved. Such words as "without prejudice", "under protest" or the like are sufficient.
(2) Subsection (1) does not apply to an accord and satisfaction."
So, I guess just before you accept the drugs from the dealer, you should make sure that you 'explicitly reserve' your rights by having them sign your contract (or I guess you can just shout it at him if you have unbiased witnesses to testify that you did).
In summary, please 'dazzle' the court with your incredible legal wit. I am sure that they will remember it as a highlight of the trial.