Not going to work like that, Item will have a state like 2018-01-03T11:36:40.000+0100
I’d do it with a second Switch type Item instead. Install expire binding and configure this Item to expire to OFF after 100 mins. Modify your rule to update Switch Item ON when bath Item updated. Look for Switch on or off to do your valuecolor.
I have a some sensors that not online every time and i just want if some time (1 hour for example) no new data received the linked item become NULL or UNDEF. This is i want to see data in charts. If i have no new data and no data in chart. Now in chart i see horisontal line with last value.