This is completely false. Pretty much all voting systems are susceptible to tactical voting, e.g. gaming the vote. This was formally proven via the Gibbard–Satterthwaite theorem[1], which showed that the only way for a voting system to be ungameable was to either have a dictator (a certain special voter who always picks the winner), or to pre-constrain the output space to only two alternatives.

This critique certainly applies to Instant-Runoff Voting, the algorithm in question here. It is known that IRV often incentivizes voters to not rank their favorites first [2].

[1] https://en.wikipedia.org/wiki/Gibbard%E2%80%93Satterthwaite_... [2] https://electionscience.org/library/tactical-voting-basics/