The trigger decision "tool" is a service in all but name for MT.
It maintains an internal cache of configuration and per-event data for each processing slot.
Mechanisms are in place to update these caches when integrated with the xAODConfigSvc, however for the RAWtoALL workflow for Run2 data we still currently need to force updates also for the deprecated TrigConfigSvc.
There appear to be other crashes when the legacy feature access code is called concurrently. These will be followed up in a future MR.