RJ made several statements about the True Power in the past:

"Shielding against the One Power will indeed stop someone from reaching for the True Power." And that "neither the One Power NOR the True Power will work in a stedding." Moreover, "with the True Power as well as the One Power you can burn out". On the other hand, an OP angreal doesn't work with the TP. And "if you try to gentle a man or still a woman who's capable of using the True Power you'd have to use another method". Furthermore only channelers can theoretically use the True Power, if the DO allows it: "Access to the True Power is a matter of wanting it and the Dark One letting you. NOT black cords. In Prologue to The Eye of the World, we saw Ishamael use the True Power to Heal insanity. The One Power can not be used to Heal insanity. True Power used at Shayol Ghul will fry you instantly." (this speaks against the idea that Rand will use the TP to defeat the DO). Finally: "it is a really great honor to be given the ability to tap into the True Power. Which is not inherently stronger than the One Power. It's not that it is stronger in any way. It is just something that does not have some of the limitations of the One Power. Other people can't feel you embracing it, or using it, like the One Power." (that the TP isn't stronger seems a bit in conflict to Rand's thought that using the TP is in his view as powerful as using the Choedan Kal).

From this one can deduce that Semirhage couldn't use the TP, when she was a shielded prisoner. Similarly Moghedien probably couldn't use the TP, when she was held by the a'dam, because the a'dam can cut you from channeling.

Therefore normally Rand also wouldn't have been able to channel the TP, when he was controlled by the Domination Band, because Semirhage forbade him any access. Rand could only channel the TP because of his link to Moridin, who of course wasn't shielded in any way. Thus Rand used Moridin's Power. It's basically the same what the Egwene does in the circle with the novices during the Seanchan attack to counter the forkroot. The DO probably didn't even know at first that it was Rand who used the TP.

This leads to the question if Moridin could actually know that Rand would be able to use the TP via their balefire bond and if he really wanted this. It's believable that Moridin doesn't know, how the bond works, as he states in TGS, ch.15. He expresses that he doesn't know what would happen if they would kill each other (therefore Moridin gave the order not to harm Rand). If Moridin and the DO didn't predict this possibility, the true plan was indeed that Semirhage should capture Rand with the Domination Band, as Moridin and SH state. Currently I tend to believe that the possibility that Rand would be able channel the TP wasn't foreseen by the Shadow. Moridin and SH simply wanted Rand captured at SG.

Of course, now - if Moridin didn't tell it his master before - the DO certainly knows at last that Rand and Moridin are linked and that Rand can theoretically use the TP. This might put Moridin in a bad situation, because the DO as THE big control freak might mistrust him and perhaps won't let him channel the TP anymore. On the other hand, the Shadow could use this opportunity to force Rand to channel more of the TP to taint Rand or Moridin could even try to kill, burn out or control Rand via the bond (or vice versa, Rand tries to kill Moridin that way first).

So, the questions are: Did Moridin tell the DO/SH of his bond before TGS, ch.22? Could Moridin really foresee that Rand will be able to channel the TP via the bond and would he want that? What will be the DO's reaction to the bond between the Dragon and his Nae'blis?