Don't forget they went a step further: After experimenting on the children they'd place in control of their Warframe abominations, they decided they needed a handler who could control them. Who do they pick?
They grab one of the Sentients trying to infiltrate them and apparently try brainwashing it with the mind of the children's mother figure, who the Orokin executed by the way, to make her care for and guide the Tenno.
They literally combined every enemy they'd ever made into one super faction. And it was a shock when they turned on them.
Did nobody think, "Hey, y'know what the Tenno, Warframes, Sentients, and Margulis all have in common? They all really fucking hate us! You think combining the first two into super weapons and the latter two into their sole controller might end poorly for us?"