Lima Juliet,
If Israel did in fact ask for a two seater (I haven't seen that reported anywhere, but I don't see everything), it would not be so much that LM refused. First US Gov't would have to approve such a thing, and then the question would be would there be an adverse affect doing that h on the rest of the program domestically and internationally,. Also, who would pay the considerable cost of developing such a craft. If you say Israel, don't forget that a significant portion of their defense funds come from the US, so would we be willing to cough up what it would cost?
IF those questions could be resolved I suspect LM would be thrilled to take their money.