I see both sides of the argument, but I think that he would need a nerf if it wasn't for one thing: he provides, at best, average damage. He has the small crit chance buff on his LS, but aside from that, he deals mediocre damage. You can take him on trials, but likely his useful LS will be locked at some point, so all you have left are his buffs, of which none are over the top (minus the shield bugs, like shields not even breaking during Glorious). Speaking of which, on my first couple tries at Trial 005, I took Tridon, and was stuck on Zev's healing loop, because I lacked damages (I took a very defensive team based around surviving Glorious' and Endless'). As trials that require dealing specific amounts of damage appear more frequently, Tridon can become more of a liability in the landscape of LS lock and buff wipes. High(ish) costs and passable damage; he trades off his damage for utility. Honestly, I think he is fine the way he is because of this. It slightly limits his uses and I can see instances where Deimos would be a much better choice than Tridon.

This is all just my opinion though, some things I have said may not be "right" but this is my impression of him since I rolled him on accident the day he came out. I used to think that he needed a nerf too (Double Tridon lead made Maxwell so easy, but I've also been able to beat Maxwell with a 4 Man squad using newer units) but I think Gumi did a decent job on his 7* with buffs in appropriate places and not going overboard. His kit needs bugfixes, but other than that, I think he is fine where he is.

tl;dr: Tridon doesn't need a nerf because LS lock and Buff wiping makes him a liability in situations because of his lack of damage and high(ish) costs. He trades off damage for defensive utility.