Using Outlook for Android in business environments for email and scheduling
Typically, using Outlook on a PC to access company email is done from within the company network or via secure VPN. Moreover, you can't compare Outlook.exe to the Outlook for Android app. The former is very well known and was, indeed, produced by Microsoft. The latter is not originally a Microsoft product. They bought it from Acompli and it really is anyone's guess how secure it is. In addition to that, the connection methods are probably different.
What bothers me a little about the company stance, though, is that if they don't want people to connect to their Exchange server with mobile devices, they shouldn't be offering the connection.
Nevertheless, they make the rules. The employees must abide by them.