You could also take the access key, then let Rand use the TP not only once but several times (without the CK as a "substitute drug" ). If Rand is then eventually completely evil, corrupted & addicted you might decide to give him the access key back to destroy everything. Otherwise Moridin or another DF might use it.

As it seems now, the supposed plan to corrupt Rand was again completely idiotic: 2 of the most powerful Forsaken are dead, while Min and Rand live even more happily.