Here is a possible way of changing the RunTime version of the model file to 2.0, so you can import the model.
You'll need a tool from Microsoft Research, called ILMerge. You can download it from here: http://research.microsoft.com/en-us/people/mbarnett/ilmerge.aspx.
Once downloaded and installed (it installs to C:\Program files (x86)\Microsoft\ILMerge) you can change the target version from the command prompt, like this:
ILMerge mymodel.axmodel /targetplatform:2.0 /out:mynewmodel.axmodelYou can use the ILSpy tool to verify the target platform. Get it here: http://ilspy.net/