What happens if one person goes on strike?
They get fired.
What happens if enough people go on a strike?
The company has to cave.
There is no difference between this and a strike. Just like with striking if enough people are willing to take the risk the goal will be achieved. If not it results in a loss.
By actively opposing the activism you are ensuring the goal will not be reached. Which in the end will not even be to your benefit if you want ceasefire voters to vote for Harris.
In your analogy, Republican voters are the massive number of scabs coming in to replace the striking workers and thus making the strike ineffective or even counterproductive.
But also… You do understand that this isn’t a strike, right?