I run the Steam version of SH5 and TWoS 2.2.15 under AVG Internet Security with full anti-virus active and full firewall control on at all times. My Steam and SH5 installations are not installed on my main C:\ drive
Steam updates I have received only appear to be updates to the Steam application and not SH5, so the updates also have not affected my system, or the SH5 installation.