His name was leaked. Leakers have a habit of suiciding themselves around the Clintons. FBI seizes evidence so that it can not be tampered with and the witness can be "arrested" or taken into custody for their protection. In this case, an arrest was not necessary because without the evidence, the whistleblower's testimony is worthless. So he was spared arrest because the real threat to the Clintons was the evidence that was seized.
Almonds
>https://earthquake.usgs.gov/monitoring/operations/heliplot.php
Ringing the bell of Freedom. _Freedom