While you are mostly right, I think it's worth being careful here. Garrett didn't say that only Po calls him that, the computer near Nash said that. Obviously, not everything in that scene can be taken at face value.
Including the part where Nash/The Faux Clairvoyant/Whomever says, "I don't like to be touched."
That's a callback to an earlier episode where Po mentions that The Clairvoyant doesn't like to be touched.
Who did Po tell that to? Raina.
So.....why, exactly, would (Allegedly) Garrett-Clairvoyant bring up that line to Coulson and Company, to whom it has absolutely no meaning or context?
Everything you guys attribute to the voice of Garrett in that episode makes no sense at all in context. Everything *about* that episode makes no sense at all in context, if you take "Garrett is The Clairvoyant" at face value.
If Nash is a patsy, and Garrett The Clairvoyant, as you guys believe, then you have to operate under the assumption that
(a) Garrett and HYDRA would kidnap a useless, forgotten quadriplegic from an obscure Georgia nursing home;
(b) They'd drive him 6 hours to an abandoned racetrack in Pensacola, Florida;
(c) They'd dig down not only beneath the *racetrack,* but about
four levels below the sewers to set up an elaborate maze and a fake villain's lair to trap Coulson;
(d) Garrett seriously thought that Coulson would fall for the bait in Macon, GA, and pick *this* red herring (one of nine) to go exploring;
(e) they'd risk Deathlok getting killed by Coulson's team;
(f) they'd risk Coulson getting killed by Deathlok;
(g) they'd risk Garrett and/or Ward getting killed by Deathlok;
(h) they could hack into Thomas Nash's speech assist program;
(i) they could pull off a believable "conversation" between Fake Clairvoyant (Nash) and Coulson through this hack;
(j) that Garrett and/or a HYDRA flunkie in another room would embellish this conversation with phrases that would have no meaning to Coulson ("I don't like to be touched;" "there's a force you can't possibly comprehend coming back for you and Skye, and Skye is going to die", etc.)
(k) that an innocent man like Nash would just sit there and do NOTHING to try to alert Coulson that somebody was putting words in his mouth;
(l) that Ward would botch this oh-so-elaborate plan
completely by shooting Nash when he started talkin' **** about his girlfriend.
My theory? Operates on four simple precepts:
a) Thomas Nash was The Clairvoyant. He was a known psychic, who was part of a top secret SHIELD program called Department H (which in the comics, plays a major role in the history of the X-Men), who suffered a debilitating stroke that left him paralyzed.
b) Nash used his contacts (probably including Edison Po) to build him a lair far from civilization, but he would stay in contact with the rest of the world via his computers. He would use the knowledge he gained from endless hours spent data-mining to create the mysterious online persona known as The Clairvoyant.
c) Coulson used genuine detective work to track The Clairvoyant to his lair. Nash confessed, and began telling Coulson his plans (as all supervillains are required by law to do). Ward got scared and angry when Nash started talking **** about his girlfriend, and shot him.
d) Garrett decided later on to assume the identity of the dead Clairvoyant to hook Raina and Quinn and use their resources to further his own greedy mercenary quest for More Stuff. Because the only people who were in any kind of position to rat him out and expose the truth were already dead (i.e., Po and Nash).
Feel free to continue to drink the Kool-Aid and believe in the convoluted and twisted plot-orgy that is required to make "Garrett was The Clairvoyant all along" work. Me, I'll stick to the simpler explanation, because that's almost always the one that works.