I agree with the final conclusion, but this is a terrible way to measure system latency!

For starters, most exchanges block icmp packets, precluding a ping-based measurement.

Latency should be measured by actually going through their systems. For example, after sending a FIX message to IB, it's not known how well their FIX processor performs (at the very least, they have to do risk checks, so its not just cut-through).