Or just doesn't have much experience with (salary) negotiation, which, for most roles that aren't sales or HR, isn't necessarily a problem. The people who do this for a living (employers, recruiters, etc.) are always going to know the rules and the social norms better than the ones that don't (most employees).

I don't really know what you mean by "ridiculous" in that situation, so it's hard to draw any conclusions, but I will say that most good engineers are pretty bad at negotiation skills, and IMHO withdrawing an offer is quite an extreme move.