This isn’t a valid way to do it. Because it could be that everyone’s SECOND choice would have been the eliminated choice, but their first choice was eliminated in the first round.
This has caused problems in actual elections in primaries, for example, where the winner of the primary might actually only be favored by a minority.
For example, if there are choices A to D and choice A gets 39% of the vote, but the remaining 61% would put A as their last choice, then in a proper run off, A would actually lose despite having the most initial votes. This is because B, C, and D might actually be splitting the vote due to similarities. I pick B, but I would be happy with C or D. Others do the same, but for C and D.