Not really your point, but if somebody gifted a $500 tandem/boat anchor for a $30MM co, that might indeed be a red flag. A $500 tandem is probably a boat anchor no matter what the circumstances are...
I (think) I know what you’re saying, what I’m saying is that if I said I was interested in your billion dollar automobile startup, and bought you a car as a gesture, you might be excited, until I handed you the keys to a used 1998 Hyundai Excel.
Unless I really am missing the point, because a $500 bicycle really is a pretty cheap machine these days, let alone a $500 tandem.
It's the thought that counts right? Tandem is the name, they are gifted a tandem bike, which reinforces the symbolism of doing something together. I'd hope it would be perceived either neutrally, or generate some very small positive feelings, but not negatively.