Done and it's a good idea to add it but most likely, the result won't be very representative because most votes are already submitted due to one vote for each Bitcointalk account. Maybe we can screenshot the poll, save it, reset it and start it again. We might run it 1 year (or 2 years) and will see how the public opinion has (possibly) shifted.
Seeing Woodie's suggestion made me realize that the poll contains 3 websites which were moved to the eliminated ones, therefore I believe they should not be part of the poll anymore: SmartBit, Coinmarketcap Block Explorer and Bitcoin.com.
Besides, if I remember well, this poll conatined initially all the explorers listed when OP was created. Since then many other websites were added. Perhaps the poll should contain now also the other explorers added?
It's a really difficult decision and maybe, our best solution is, if we do it like that:
First step: screenshot the current poll and save it (normal picture or even archive)
Second step: reset it and start it again, where we will add all current sites and remove inactive sites.
Because changing a bit of it now will invalidate the poll, when old votes are getting removed and some people already submitted their votes but would vote for new Blockexplorers now, instead.