He should write the offer you want. 7.5% isn’t that much.You might not get it but that isn’t a high reduction. If there is a really valid reason he should be able to offer an explanation that doesn’t feel like arm twisting to you. That would be something like, “It already has 4 offers and I know that yours won’t get it, would you like I try to discuss a back-up offer with the listing agent”?
One problem now, with getting another agent to write you an offer on that particular place is that this person showed it to you and can claim to be procuring cause. You would want to put in writing that you are going with another agent because he or she is giving you too much hardship about writing the offer you like. They could still try to sue but it probably would not come to that. You could just tell them to write the offer or quit. Dump them if they don’t come around.
The principal gives the orders and if he doesn’t like the way you do things he should quit on his own behalf and not try to bend you to his will.
If you get another agent ask them upfront if they will write low offers or even “what the hell you never know” offer, in case you might want to try that.