Never burn bridges, just not worth it. Ive had referrals from people who were a complete hassle to work with both as clients and as co-vendors. I booked a wedding recently for 8k from a couple who was MISERABLE to deal with, but ended up loving the photos. you just never know.
People talk - and although you may have done the right thing in turning down this wedding - the way you did it has probably damaged any positive reputation this vendor has towards you and they won't refer you any more.
Obviously this couple liked your work, even if personally they were hard to handle as a vendor at a wedding. Now you not only burned bridges with a potential client, but also with a vendor who could have reasonable influence in the community.....