I think the key part here is how every step of the way they just ignored the textbook on how to do this ethically.
For starters the implant caused bleeding in the female monkey, that should have been caught way earlier by the staff, and the experiment consequently aborted. If you go a step further and extrapolate here you can start to suspect that they didn’t even do the basics and likely skipped non animal testing on the compatibility of the implant with brain matter.
This reads as if they used animal testing in place of simulated prototyping which is absolutely not how this is supposed to be done. Animal testing is that last step when you’re 98% there already, not if you’re just finished with the prototype.
We can grow cells in the lab, so what they should have done is test this implant on artificially grown brain matter in the lab, that would have shown them that the implant harm the attached brain without actually harming any living animal.