To be even more brief:
What you are trying to achieve is not possible.
Every Alien which is marked as STR_ALIVE_ALIEN and has a appropriate Rank will be sent into the Alien Containment, and units in the Alien Containment are automatically made avaible in the Research Options.
This behaviour is as far as my knowledge goes hardcoded and for good reason.
However you could make the Alien Containment unit require some depenencies to get unlocked, move it further back into the research tree prolonging access to some tech's you usually wanna have quick, like Hyperwave Decoder for example.
It is also better to give the interrogations more meaning, for example you can add a getOneFree list towards any Soldier Rank, automatically unlocking a weapon or ammo type by random, which also would mean they would be avaible for research mutiple times.
The example i posted before mentioning the YAML anchors will help with this to a great deal, since in the end you only have 1 place to change your lists and it would be automatically applied to all the other places the list is called. Also removes redundencies.