I work in the aerospace industry and while blender is a good tool for learning the basic of 3d modeling, it would be a poor choice as a solid 3d modeler. It also lacks the dimension-ing aspects of any CAD package such as blueprinting. Simply put, blender is a great tool for prototyping and making things that otherwise will never touch the real world. Trying to produce a viable product in these studios would be at best difficult. If he is looking to brush up on his skills I would recommend trying to get a student license for AutoCAD(or desk). Typically, you only need to know someone in ANY school to apply for one and they simply give it to you. The only downside is that models created on a student license cannot be manipulated on another machine, but since he only wants to practice this shouldn't matter.
The packages we use at work are Siemens NX and Dassult Systems CATIA. Both of these programs run off of floating licenses that cost $10,000+ per seat! If he's really desparate, call up to your local community college and see if they offer any CAD design classes. These are typically only $300 or so for a semester, and it will get him the student status he needs to obtain a student license.
Tell him good luck for me!