If he was sure it was unwelcome, then yes, that would be a very straightforward solution!
What Oliver actually says is, "I wish I'd been smart enough to discuss this earlier before it became an immediate issue. But, Emily, there's a very real sense in which you're one day old, and deciding who to be and what to make of yourself. I don't know what sort of person you'll become because you don't know either. My life up until this point has made me scared of rushing right into things. If you decide to go on the glorious adventure of falling in love with me much faster than I'm courageous enough to let myself fall in love with you, that does run the risk of my having not decided on you at the point that you've decided on me. I have my own equivalents of daffodils and it would not be fair to ask you to cough them all up to me immediately while you're one day old."
(To be clear, Oliver totally would ask her to cough them all up on day one if Emily was the prettiest girl in town and looked somewhat older. Furthermore his daffodil list would include him being allowed to sleep with other women, but Emily would be allowed to sleep with them too.)