I've seen that kind of thing expressed before and it bugs me because there's zero reason anyone would ever think that science is omniscient. Science is based on the best evidence we currently have, the models that are most useful to us, and all of it is subject to change as soon as newer better evidence/models are discovered which contradicts or improves on what we currently have. There are countless unknowns in science and that should surprise no one.
If you told me there were no elephants in your bedroom and I countered with "Consider the possibility that there are four microscopic elephants in your bedroom you did NOT notice. We should accept that you are not… omniscient." you probably wouldn't be convinced that you should stop saying there there are no elephants in your bedroom. It might be more accurate to say that you don't think that there are elephants and that you can never be certain, but since it's obvious that you never can be certain it's not a very useful point. It's perfectly fine to just say that your bedroom is elephant free. The "as far as I know right now" is implied and understood.