As they have survived infected for such a long time, I think all of the old Rembrandt cultivars probably can survive a good while longer with proper care, so in that sense the virus is probably benign to all of them. If you want to be extra sure you could just cover them with a piece of horticultural fleece or similar until bloom time and cover them again after bloom has finished. On the other hand I have never seen aphids on tulips here, but don't know if aphids are a problem in your area?
Be sure to disinfect tools after handling or preferably, don't use tools on these tulips. Break of the seedpods with your hands (not your nails ) and be careful not to splatter the sap around. Actually this is a good advice when handling any plant as virus are almost always present, but not all viruses causes problems at first. Sometimes problems may not show until several viruses infect the same plant, seriously weakening it.
Yes, my tulips had contracted some strain of the tulip breaking virus. If the color breaks in a normal tulip it's always virus as far as I know. In the case with Jan Reus I discarded all bulbs of that cultivar as well as other growing close to it as I had carelessly been cutting tulips for bouquets without disinfecting my pair of scissors. No big deal, these were cheap bulbs and I slept better. In the case of Slawa I just pulled the infected one, with bulb and everything (yes, I have a loose sandy soil )and put in the trash. I also had a few others of another cultivar with weird foliage that I pulled, but unsure if they were infected with a virus or not. If so they were perhaps infected in my own garden.
I think every grower probably does his or hers best to keep virus out, but no one can guarantee 100% virus free. If I buy 200 bulbs of 20 cultivars and one single bulb is infected I'm sort of okay with that, but I agree that zero would be better and for sure there are also many crooks out there! Truth be told I'm personally even more more concerned with pests, fungal and bacterial infections as these often spread a lot easier than virus and they are harder to fight. With buying a lot of bulbs/plants there are also many serious risks!!!
In the case of historic Rembrandt tulips the virus is actually part of what you are paying for. I never seen a vendor selling these tulips without telling the buyer. If you look, you will see that Nijssen Tuin also informs buyers of the virus (at the top introductory text):
https://nijssentuin.nl/141-rem...
And no the modern Rembrandts aren't as nice
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