Why the second attack on Sarif? Why take over Highland Park?

I'm playing through HR again (Director's Cut) and it's bugging me that I can't recall or figure out the conspiracy's motive in attacking Sarif the second time.

What was the hacker actually looking for? Everyone with a clue seems to dismiss the notion that it had much to do with the Typhoon. Was it the biochip design? Another attempt to steal/purge Patient X research? None of these seem right.

Also, since the conspiracy used Purity First to do their dirty work, why did they push FEMA out of Highland Park and bring in the Tyrants and all those mercs? All of their operations in Detroit at the time seemed fairly covert, and would only be jeopardized by such a presence. Were they planning another raid on Sarif HQ that was called off when Jenson and Pritchard eliminated the backdoor?