So, your logic says that it's not a waste of time for Jordy to practice shooting threes because Pitchford and Jacobson (both listed as forwards, unlike Jordy, who is a center) shot threes.
My logic says it is a waste of time for Jordy to spend time working on that shot because there is no call for him to shoot it (and, yes, he has other things to work on a bit closer to the basket).
I took a look at some numbers.
Centers (on Huskers.com rosters) in Miles' Nebraska career:
Player/Career threes shot-taken under Miles.
Andre Almeida/0-0 https://www.sports-reference.com/cbb/players/andre-almeida-1.html
Jordy T/0-0 http://www.espn.com/mens-college-basketball/player/_/id/4066393/jordy-tshimanga
Moses Abraham/0-0 http://www.espn.com/mens-college-basketball/player/_/id/51318/moses-abraham
Sergej V/0-0 https://www.sports-reference.com/cbb/players/sergei-vucetic-1.html
*Kye Kurkowski/0-0 https://www.sports-reference.com/cbb/players/kye-kurkowski-1.html
Have power forwards chucked up the three under Miles? Of course (some of them in bunches). But, so far as I can tell, no player who has logged any minutes listed as a center on the roster during Miles' tenure at Nebraska has ever shot a three. Not one.
This isn't even taking into consideration Jacob Hammond (who many thought was the first true center Nebraska had recruited in several years) as Huskers.com has him listed as a forward...but he was 0-0 as well, or Ed Morrow (who was also listed as a forward but spent most of his time as a Husker playing the center position) who also went 0-0.
Miles' system at Nebraska has a history of forwards shooting threes, but centers have no such claim.
Unless you think he is a forward, there is no history (that I can find) that would dictate the need for Jordy, as the center he is, to shoot threes in this offense. It has literally never happened.
Considering the total lack of centers shooting three pointers under Miles (based on roster position), it is laughable to think his center should spend time shooting the shot.
You said earlier, "Yeah, because there's never been any opportunity for a big man in Miles' system to shoot treys." What you thought was hyperbole actually couldn't be more true if we're talking about guys who are listed as centers under Miles at Nebraska.
And I don't think I ever hinted that it's either impossible or improbable for Jordy to make a three. I simply said he wasn't going to shoot them in Miles' offense (because he plays a different position from the two guys you mentioned). Heck, I've seen the guy make one; the day he signed his LOI he posted a video of himself hitting one from deep. So, yes, it is clearly possible for him to make the shot; there's simply no history of guys in his position under Miles even shooting one in a game, let alone making one.
*Kurkowski was listed as a center for 12-13 and a forward for 13-14.