this is wrong.

when you give someone else a GPL'ed application, you must be able (and willing) to give them all the source code required to build the app themselves. you cannot (legally) do that if the source includes the steinberg VST SDK. ergo, you cannot distribute a binary that was built using the VST SDK.

as has been pointed out, this is largely irrelevant - no linux apps that support (even windows) VST plugins uses the steinberg VST SDK anymore, given that we have vestige.

the issues with "VST plugins" at this point in time are NOT about the VST SDK licensing, but about the hassles, perils and wisdom of hosting bits of code written for Windows.