I hadn't read anything on Thomas, but after going through several scouting reports, the 'negative' aspects the mention are pretty light. The Vikings have reached plenty, but my 15 minute research on this guy actually has me liking the pick.
Also, all of his 'positive' comments reference his excellent blitzing instincts. You don't read a ton about blitzing on safety profiles. So, yeah, pretty clear what it was about him that Flores wanted!