We must not forget that not only this market is relatively new compared to the forex market, there were even some companies that directly stated that if they found one of their traders trading this market then they will fire them, this was long ago but it still happened, so it is not surprising that even if those that trade forex have the abilities to trade this market as well, they are only beginning to do so as there was a significant effort to try to discourage them from doing so.
I'm not aware of this that companies would stop there employees from trying to source for alternative means of income with trading of cryptocurrency. I think that will be against the freedom of the employees and I think it shouldn't be the business of the employer to look into the privacy of those working for them if they are not using the time for their paid job for trading. If they are performing their jobs effectively then no need stopping them especially if they are not trading while in office or in office hour.