It doesn’t make yum crash.
This is your free choice. 
But let me be blunt for a little: we involved 3 different developers, analysed the problem and searched for solutions. I’m even willing to modify the doc for your request … and you say it’s not enough. Why should I even spend more time on it? 
PR open: restore: document third-party repos by gsanchietti · Pull Request #531 · NethServer/docs · GitHub