With a soft-fork, users do not have this choice. Even if 45% of the miners hate the change to the
rules, they cannot force a split of the chain, and must adopt it. The users will have to accept it too,
whether they are aware of it or not.
Users never have to accept it and can instantly veto any SF or HF introduced by the miners simply through inaction.
When that happens,
the receiver would have to download the new wallet software to get access to those coins
Downloading a wallet to refund some counterfeit altcoin doesn't necessarily have anything to do with the original bitcoin chain or software. There would only be a problem if the user or merchant wasn't bright enough to actually check or ask why the coins weren't accepted before swapping out their old wallet.
In unlikely even such a scenario existed their would be a very loud and widespread warning declared and developers would likely implement some emergency patch to disqualify the mining cartel trying to hijack bitcoin. Sure there would be a few people accepting some counterfeit tokens , but this is no different than a 51% attack and much less of an issue than all the fraud that regularly occurs within Fiat.