Yes, it is still safe
It has not yet expired & they were only discontinued because they couldn't add LATCH anchors to it (I *really* wish they'd figure out how!)
My 6 y.o. is just at the height limit of our 2002 Laptop. She is still using it in our housemate's old Volvo because her particular vehicle is very incompatable with any other option. Ideally it should be used in the center, but knowing that this is the safest option considering the circumstances, I feel fine buckling kiddo into it.
Also, I've talked with other CPST/Is about this & for my own personal use, I feel comfortable using the Laptop until 10 years after DOM because that is NHTSA's absolute cut-off & because the Laptop does not have a hard plastic shell which could crack. Using it after the 6 year mark would be a drastic last resort option, but one that I wouldn't hesitate to take advantage of under specific circumstances.
The Laptop crash tests like a 5 point harness. It just lacks side impact protection. When it can be used in the center and/or the vehicle has rear side curtain airbags, then this is not a major concern at all. The Laptop may very have saved another CPST's children's lives (she is also a mod here & may respond with her story, but you can use the Search feature to find more threads on this seat, too).
I love our Laptop & feel immensly grateful to the CPST-I who sent it to us to meet our indivual needs
If I had a more typical harness option that could meet our needs, then the Laptop would be a spare, but the Laptop is the only seat that our needs so I use it with confidence