The only people I know of who don't know what the word "liberal" means, especially in the context the person above was using it, are very ignorant Americans. To be clear, even though I don't like most Americans, I'm not blaming them for being ignorant in this particular case because they have been subjected to decades of mostly uncontested propaganda deliberately obfuscating the term. But most of the rest of the world knows what everyone is talking about when saying "liberal" and knows it's a right wing ideology. And everyone shouldn't have to hold up the conversation to preemptively explain what the word means to those who don't already know. People are generally expected to pick up the gist of a sentence or point via the context of what's being said. The context was perfectly clear and it just sounds like concern trolling to go on about needing to hand-hold and dumb down the terminology being used for "the average person."

You could use "corporatism" which has kind of taken over that definition in common language

No one says "corporatism" in the real world. The better suggestion for an "alternative" is to just say "capitalism", because that's accurate enough.

You could use “corporatism” which has kind of taken over that definition

"Neoliberalism" rather. Though that's more like mask-off imperialism. And "corporatism" is just capitalism but when you don't want to admit that the problem is capitalism.

Either way liberalism is the same idealist, individualist culture/ideology that emerges under capitalism to maintain that capitalist mode of production, and must be destroyed along with the mode of production it sustains.