Is Final boss (rouge process) of this game a scam!

[AVG GMR]

After completing my game, I started playing NG+
Turns out nothing is new expect some new enemy placements! No new implants, no new weapons, no new Armor(exo), etc!
Traditionally every boss of this game have 2 ways to kill it! One way will drop a broken weapon as reward and other way will drop as "V2.0" version of the weapon which has some special effects!!
There is special case boss called "Black Cerberus" which has unique way to defeat him, and it will grant you not only his "V2.0" weapon but also his full armour(exo)!
So I thought if not in base game but NG+ might have a unique way to kill final boss that can grant me his full silver plating Armor(exo)!
I was excited, I thought over and over and the thing I came up was, only 1 way was remained unchecked which can possibly be the answer to my curiosity. That was killing the monster form of final boss and then Overcharging the console!
Turns out after the "monster boss" drops on to 47% of health he becomes untargatable and invulnerable! You can not hit or damage the monster boss, but still I did not give up, I used firebug throttle V2 to see if I can do fire damage to it! I also used judge V2 and shot energy arcs towards it. But no results no affects! Got fed-up and finally I went over in second phase of boss fight and cut him half from torso but it only droped a weapon "mimetic edge" which I already got from 2 NPC along the way! I felt so disappointed and scammed!
My only concern is why make "The final boss fight" only 1 way!? Why not make him as black Cerberus boss to drop it's Armor(exo)? Because every humanoid NPC of this game drops body parts as player cuts them! And if you say rogue process is not human but nanites then so are chrysalis bots! And they still drop Armor(exo) pieces!!!
Why you mentioned there are secrets in NG+ which are not and make the ending of this game so lame and plain?

[AVG GMR]

Just for record, I know rogue process boss drops 2 weapons, "claws of gestalt" and "mimetic edge"! I got both of them! But imagine getting same weapon which you found from a regular NPC of NG+ after killing the final boss of this game!!!
Also I don't get the logic behind making the "Monster form" of rouge process invulnerable after dropping half of his health and forcing players to go on in second phase of the fight!!
I felt so stupid when I ignored the monster boss in my 1st playthrough for not finishing him off completely!! Turns out I was even more stupid to think that he was actually killable in that form!!