Isopropyl alcohol to clean Nylon plastic
Your nylon plastic should be thoroughly resistant to concentrated isopropyl alcohol.  

According to this encyclopedia.com entry, nearly all of the nylon produced (in the US anyway) is one of two types: type 66 and type 64. Each of these is stated in the article to be insoluble in water and most organic solvents, but soluble in strong acids.  

As some anecdotal evidence of nylon's resistance to common solvents, this Quora discussion referenced a frustrated biker's need to find a suitable solvent for removing some nylon that had melted onto a motorbike exhaust pipe. There was really no good consumer-type of solvent listed (and nothing remotely chemically similar to isopropanol), and it actually included a link to a patent for a compound specially designed for dissolving nylon-based materials, just because they are so chemically resistant.  

That all said, it wouldn't be a bad idea to do a "spot test" of the isopropyl alcohol on a small, inconspicuous as possible piece of the plastic. There's always an outside chance that it's not exactly what you think it is or that for some reason your particular nylon-based plastic is not as immune to a solvent like isopropanol as the above arguments imply that it should be.