The solution was to remove the following line from the .csproj
altogether:
<ProjectTypeGuids>{42C0BBD9-55CE-4FC1-8D90-A7348ABAFB23};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
The project can then be loaded normally in Monodevelop.