Altium: Export/Package Read-Only PCB or Project
No, there isn't any way to make your project read only in Altium, to avoid accidental changes you should simply lock all your components and features. 

There are alternatives that I have used 


Send a stripped down design or only the PCB file and a reference schematic 
Send odb++ or an exported CAD data (e.g. legacy ascii fileformat) that makes it less trivial to pretend to be you while providing more data than gerbers and basic assembly data .
Find consultants you trust to  respect your IP,