BizTalk orchestration expression shape unable to write entries to Windows eventlog

I were just in the process of debugging an orchestration in BizTalk 2006r2 the old fashioned way: writing eventlog entries from an expression shape when I noticed that I got an exception in the eventlog instead. The exception was of type "Security Exception" with an inner exception detailing "Requested registry access is not allowed.". Easy enough, a quick google turned me to this blogpost and the solution which is to add the appropriate BizTalk service account to the eventlog node in the registry. After setting the permission, writing entries work.