I believe they are mostly talking about maxxing out your CPU usage since I am sure they oversell their CPU availability. This could really be fixed with affinity settings, but that may also interfere in peak moments. Im sure they have that in there so that they can kick you if you start holding you CPU at 100% load 24/7
If they advertise with certain features then you should be able to use those features.
They'd have some form of scheduling that would just restrict your CPU usage there they aren't going to shutdown your box just because it's under load. This would be for when you are making millions of unnecessary api calls or have a virus spamming the local network.
They provide for "bursting" of shared resources as needed. If you are under your resource cap, you're fine. But if you're constantly needing bursts out of the shared resources, you need to move up to a higher-resource tier with more dedicated resources.