My first response is "why?" From there we can explore what the actual problem is. If it's a rational "that won't work" with a plausible reason, we can just drop it there.
If I'm unsatisfied with their reasoning, I can either lobby for it if this person has influence enough to block it, or just ignore the person otherwise.
Unfortunately, in politics a good way to block something is to bury it in paper: "Hey that's great! Draw up a proposal and we'll bring it up next meeting!" For this you need to go full-on political, with all the crazy games that entails. At this point you have to decide whether it's really worth the energy or not.
I had one particularly terrible manager whose response to any new idea was "Great! Make a Github issue for it!" Some employees even made a meme of it. By the time my tenure there ended, the GH issue list was thousands of entries long with no action taken on anything, and no way to find anything in that huge pile anyway (basically a garbage dump by design). For these kinds of situations, don't expect to have any impact.