There are always alternative frontend websites for twitter, nitter for example, if you really need to see updates someone has posted then you type their username in to one such frontend and can see their tweets listed.
I tend to agree with much of what Musk has done, his anti-censorship stance is fairly nice*, as was the principle of sacking masses of corporate box tickers... but if he thinks making viewing tweets a login-only action is a wise idea, then he will destroy the usefulness and user-counts of the platform that he payed so much to buy. Twitter isn't much use for much really, but the whole idea for anyone who does use it is to be able to share quick messages with vast numbers of people online and direct them to webpages where the twitter poster has their actual full-length articles/videos/content/.... It is supposed to be "micro-blogging", not "social media" and where "social media" is all about having conversational** two-way interactions with other users with accounts, "micro-blogging" is a one way means of getting links widely shared. Nobody will be interested in sharing links only with the small number of logged-in users, people who want to post things on twitter want the maximum possible numbers to see them, and that means mostly people browsing past and following other links who can't be bothered to waste time setting up a twiter account.
*it would be nicer if he meant full anti-censorship rather than the position of "free speech within law" where twitter holds out against politicians on-the-moment speeched, but backs down to a government which ticks a few more boxes, shuffles some extra papers and signs censorship in to legislation
**we all know that very little of it is coherent enough to be considered a conversation any more, but the idea was there, at some point in history, perhaps