>Protecting children wasn't a serious motivation of many people who supported it?
Probably. People were seriously concerned about communist infiltrators in the 1950s. People were seriously concerned about Dungeons and Dragons and backwards masking and secret pedophile cults back and the "gay plague" of AIDS in the 1980s. People were seriously concerned about Muslims after 9/11. People are seriously concerned about transgender groomers and "the wokes" and Chinese mind control through TikTok today.
People are always sincerely concerned whenever the government gasses them up in a moral panic. The ruse comes from the government's response, because during moral panics Constitutional rights always seem to get in the way of Something Needing To Be Done.
Unfortunately one has to assume, by default, that any law passed under the aegis of "protecting children" nowadays has no actual intent behind it other than eroding Constitutional rights for the sake of ratcheting up fascism.
The other half of the problem is that the direction of these moral panics tends to embrace and expand the existing fundamental problem. Here, the tech industry desperately needs some competition in client software, which is currently being prevented by the anticompetitive bundling of client access software together with communication/hosting services. If there were competition, a parent could let their kid communicate on facebook/tiktok/etc with a client that worked in the interest of the kid themselves rather than being forced to take-or-leave the deliberately-designed-as-dopamine-traps singleton proprietary apps/webapps. But trying to fix that fundamental problem would likely step on too many moneyed toes and thus end up dead in the water. So instead this bill was aimed at creating even more of an anti-competitive moat in the hopes the tech giants would get on board.