I don't totally agree with this. There is risk in bitcoin, low risk or not. The risk is low when you're holding for a long time that's for sure but there is risk. So instead what you should say is that the person should say "low risk"No investment doesn't involve risk. Even treasury bills have risks even though it's low risk.
If you're investing for the short term then it is no longer "low risk" but "risk"

When talking to people above bitcoin investment, especially newbies I make sure I stress out the risk part so they won't have the idea that they can't lose money or that profit is guaranteed withing a certain period.