If you 300ms latency then yes, you defeat this detection mechanism.
Only if the detection mechanism is looking at that single IP and from a single location.
Find the ASN(s) advertising that network and figure out their location.
Even within the ASN there may still be multiple hops, and those IPs may be owned by others (eg the hosting facility) who are not playing the same latency games.
We operate servers for the purpose of measuring the internet using a wide variety of methods. We have more than 1,200 of these servers distributed across 530 cities, running not only ping but traceroute and many other types of active measurements.
In addition to active measurement and research, there are many other sources of data we use. Also, we are actively investing in R&D to develop new sources. Adding just 300ms of latency at the end of an IP address would simply appear as noise to us. We have dozens of locations, hints cut through the noise.
We welcome people to try to break the system. Perhaps it is possible to dupe this system.