You would rather what a bus?
The sentence could be read as "I prefer to be on the road with a bus since I think it's safer". Or it could be "choosing what's most dangerous, I'd rather say it's a bus".
It's also not clear what the perspective of the speaker is. It might be that a bus is safer for the rider, but more dangerous for cars around it. So would he rather be on board a bus, or rather on the road with a bus?
No ambiguity in that comment that I can see.
EDIT: I guess the use of rather in this context could be a colloquialism?
"the omission from speech or writing of a word or words that are superfluous or able to be understood from contextual clues."
So: I would rather [have] a bus any day.
That's more on you than the OP. It's hardly an unknown phrasing.