You can refuse to sell your home to a buyer who intends to use it as an investment property. However, if you are working with a realtor, expect your realtor to put pressure on you to accept the deal. There is also the question of commission owed. The listing contract you signed has a clause that states - you will owe a commission to the brokerage provided your realtor brought a willing and able buyer to purchase your home. This means if the buyer doing a 1031 exchange was willing and able to buy your home, then you will owe a commission to the brokerage. Listing contracts are worded that your home does NOT have to be officially sold in order for the realtor to collect a commission. Just that the realtor brought a buyer who is willing and financially able TO buy your home = a commission.
If you want your agent to bring another buyer, you need to expect your agent to start getting lazy because there is no incentive to bring a different buyer. He / she already collected your commission. Why work to bring a 2nd buyer?