Again, I encourage you to read some of these Supreme Court cases. At least half of the justices are decidedly conservative in their interpretation of the Constitution. The fact that firearm ownership is even still considered a right instead of a mere privilege is due to the conservative Justices adhering to a strict, traditional interpretation of the 2nd Amendment in the Heller vs DC case.
The fact that you summarily dismiss their role in all of this and label most of them as liberal tells me that you are ignorant of why you still have gun ownership rights to begin with.
Also, I don't see anyone here arguing that we make RPG's or artillery pieces legal for civilian ownership. So obviously even the most diehard 2nd Amendment supporters acknowledge that our gun ownership rights can be infringed to some degree.
I know diehard gun control advocates won't stop with bump stocks. But the rest of middle America, the majority of which supports gun rights to some degree, does want there to be some control over automatic weapons. And my stance is less about appeasement and more about enacting regulation/legislation on our terms instead of their (gun control advocates') terms. I'm firmly convinced that if we don't take the initiative in crafting regulation/legislation that at least allows for law-abiding citizens to apply for and buy bump stocks in a regulated manner, a much more unfriendly administration will come along and prohibit their ownership all together.
Also I just don't think bumpstocks are worthy of the gun advocacy groups spending their political capital on. They're mostly impractical for everyday shooters (and consume a lot of ammo). They do skirt around the intent of the 1986 NFA, and it's pointless to argue otherwise. And there are causes much more deserving of our attention (over-turning state-specific bans, loosening restrictions on suppressors, concealed carry reciprocity, ect.).
I care about gun rights, probably more than you because I live in a state that expressly forbids certain types of firearms due to how they look. I just think starting a long and costly political fight over bump stocks is a waste of time and effort.