Wow, the 'I love all dogs, but' sounds suspiciously similar to the equally popular 'I'm not racist but'.
You can't claim to love all dogs if you are willing to make it's life misery because you have some unfounded suspicions of what breed it may be. Because the restricted breed laws are not designed to make owners take responsibility.
I know of a recent court case where the owners tried everything to prevent their non-pitbull, well trained and socialised dog from being declared a restricted breed by the council. They lost and now the dog has to live outside in a cage for the rest of his life. The owner considered having him pts to save him from that horrible fate, but couldn't.