I have a $20 5.8ghz DECT 6.0 cordless phone made by Uniden. Works fine all over the house. Absolutely clear and noise-free. Far better than what one could buy in the 80's and 90's for much more money.
And I don't have to be able to "see" the base station to use it. So, in that sense at least, it's definitely not LOS. Of course, if by LOS, you mean it can't use ionospheric skip or tropospheric scatter, then you'd be right. But those modes are irrelevant to the case at hand, regardless of frequency.
The more modern remote controls use digital technology to encode their signals, much as the DECT phone does. That greatly improves reliability and makes work accidents due to random interference much less likely.
What do you guys think about it being just a timer?