I know I can use the esc key to abort the scanning process but is there a setting somewhere to disable this?
I'm not 100% but, maybe unchecking these boxes?
Use VST3 Plugins Use Audio Units
I'm not sure I'd uncheck the 'Always use Latest Version of NI Plug-ins, unless the scan process is hangin up on an NI product I guess.
I suppose you could also customize which plugins are scanned here?
If you untick those boxes, the plugins would not be usable in the program. Hopefully NI will address the scanning in one of the updates we've been promised "soon".