Think about the alternatives, you could use batch-commands, vb-scripts or your own compiled binaries to manage your product. Why would a potential customer trust these technologies any more than PowerShell?
While PowerShell is considered very powerful
in the end you can do everything with any of these technologies. In the end they all call Windows APIs.
So, PowerShell is not less secure than the alternatives. It is actually pretty easy to require all scripts to be signed before the can be run (you can do the same with vb-scripts though).
Also as an administrator I would prefer a PowerShell script over a C# binary because I could quickly check and review what the script is doing.
With things like the Just Enough Administration toolkit one can limit what and when certain administrators can do certain things, locking down the system even further.
So, not allowing PowerShell in a professional Windows shop is weird to say the least.
Try managing a Windows Nano Server without PowerShell.
Why not talk to some of your potential customers and ask them about this. I'm interested to hear any arguments against using PowerShell.
Sign-Script
alias that does this easily. But so many people don't.