@Dave994 The first thing that came to my mind was that you booked, then the host saw your profile picture and cancelled. I.e., he discriminated.
However, reading the message thread, I think it's much simpler than that. The host said, "This home shares a wall(s) with other homeowners." You said, "As you can imagine, we do plan on being up late and we will be having light music and be outside in the hot tub."
Reading between the lines, this host declined because he's had disputes with the homeowner on the other side of the wall, not because he was discriminating against you. Your honesty was refreshing and he really should have thanked you for that and let you know that his bad-tempered neighbor would be having a fit over your lovely evening.