I see what you're saying, if a criminal proceeding had been brought and had failed to find proof of wrongdoing, then it would be acceptable (even in the face of a not guilty verdict) to bring a civil case because there would be the underpinning of a legal issue. Without criminal charges, then you believe a civil case has no merit. Add right to silence and protection from self incrimination.
Here's where we disagree and why:
A civil action doesn't need to be illegal. It's not criminal to slander someone. Defamation is a civil tort, not a criminal offense. In fact, only 13 states still consider prosecuting defamation as a criminal offense, and even then it's very rare.
Defamation Law Made Simple
So yes, the Laundries not telling Gabby's parents Brian had returned home without her and had killed her, even if they knew, may not be criminal which is why there are no criminal proceedings on that point. But like slander and libel isn't criminal it's not civilly right. The Laundries ignoring Gabby's family and withholding vital information did cause them pain and distress and may be civilly wrong.
Additionally there is evidence that the Laundries attempted to plan and help Brian escape, according to Gabby's family. If true, and if there is evidence of this, then a criminal charge could happen, but likely only on that issue.
Everyone agrees the Laundries actions were outside of the realm of what's acceptable, ethical or moral. We all sat with our mouths open when we found out that while the Petitos were worried that Brian and Gabby were missing, Gabby's van had been in the Laundrie's driveway for days and Brian had been home with his family. The country sat in stunned silence when it was days after Brian had run off before the Laundries alerted LE. It wasn't just Gabby's family who were astounded and appalled, everyone was, so much so that mobs formed outside the Laundrie's home in protest of their actions. We even say we understand why Gabby's parents are upset, that's because we believe the Laundries were civilly wrong.
In this civil proceeding Gabby's parents are asserting that the Laundries actions brought them pain and suffering. This isn't about what Brian did, it's about what his parents did. Again back to slander, is it normal, appropriate and civilized to cause pain to someone else and ruin their reputation under any circumstance? The Peititos are asking a jury to decide if it's morally, ethically and normal for the Laundries to have behaved as they did.
I applaud the Laundrie's attorney for making this about free speech and confusing this with a criminal trial, but this case is about feelings and pain and suffering as civil cases typically are, even while some of the Laundries actions were legal. The jury would only determine whether the Laundrie's actions were so abnormal and egregious that Gabby's family should be compensated for their pain and suffering.