Using EF to insert data into SAP Business One.

You are absolutely correct. You cannot use anything other than DI to perform data manipulation.

Because if you violate this, the warranty is void and SAP would stop any kind of support it.

Coming to your point of using EF in your project, I will issue a simple warning to you just because a basic operation also results in updating many tables. In simple words, a lot of data manipulation happens. So in case you still stick to using EF, then you will need to take care of doing that on your own.