Exchange 2010 Sp3 Upgrade, WCF/HTTP Activation Missing

I have a customers Exchange 2010 Sp1 server that needs to be upgraded to Sp3 prior to moving them to Exchange 2013. I am trying to install Exchange 2010 Sp3 update and get the following error

The .NET Framework feature 'HTTP Activation' isn't installed.  User Server Manager to install HTTP Activation.

When I add that feature I get the following error.

Add-WindowsFeature : Installation of [.NET Framework 3.5.1 Features] HTTP Activation failed. Attempt to install HTTP Activation failed with error code 0x80070643.  Fatal error during installation

Through some research I have found that by removing the Windows Process Activation Service feature I will be able to install the WCF and HTTP Activation feature and then re-install the WPA Service.

http://www.techieshelp.com/cannot-install-net-framework-3-5-1-on-server-2008-0x80070643/

My question is: Will removing the WPA Service from a functioning Exchange 2010 install cause issues with Exchange functionality? Will I be able to re-install this feature successfully afterwards? All blogs do not discuss this issue with Exchange 2010 already running on the server, only issues with install...

No technical answer here but our decision was to simply build a new Exchange 2010 box, install Sp3 on it and migrate mailboxes there as a holding server for Exchange 2013.