Dog whistling is like sealioning. I'm not saying it doesn't happen but it's the least worrisome and bothering thing on the Internet.
If someone is dog whistling they are effectively conceding the argument because they're too ashamed to make the case plainly. Just take the W. The alternative is to explain to someone (and some hypothetical audience) that you you know what's going on inside someone's mind better then they do.
And again - there are people who will literally say they are Nazi's. There are people who will make not dog whistle or beat around the bush argument but straight up I am not ashamed to say arguments for awful things.
If you like Foundation and disagree with the arguments that it's not good then engage the argument made - just saying that you think there's an unstated argument and you'd like to engage with that particular one doesn't really get you anywhere.
If you're agreeing with their viewpoint but for a different reason, explain the reasoning.
If you don't feel like typing out a substantive comment, why would anyone want to read the comment you barely felt like typing out.