It's insanely few, but also isn't that possibly an advantage? When lots of people's transfers are intermingled that means the possibility of separating out one person's traffic from the rest is harder.

Those user's traffic is cleanly separable at the destination, so this attack is always possible from some vantage point and isn't a defensible position. So malicious exit nodes are the real threat. Your reasoning would apply better to guard nodes.

No, it makes it much easier.