In their original post on his suspension they didn't think they had a good argument for suspending Trump based on the current situation. They had to resort to a hyper-partisan reading of "To all of those who have asked, I will not be going to the Inauguration on January 20th." [0] for example, rather than an appeal to something more reasonably interpreted as dangerous.
Then the so-called "Twitter Files" [1] provide confirmation of what we already sort-of knew that the inside of Twitter was a highly partisan environment creating internal pressures to boot Trump for political reasons, looking for excuses and testing attempts blindly. Note that the process outlined to ban him was to keep testing tweets, the policy team returned "no violation", then they tried the next tweet. Then eventually the executive got impatient and seem to have overruled the process to get him kicked off.
Compared to that, what Musk is doing is rather mundane and palatable. It is more or less up front that he doesn't like the journalists targeting his affairs, and isn't politically motivated or likely to be meaningful.
It has been a couple of years now, there was a big investigation that turned up nothing. Trump is running for president again the usual way and just launched an NFT token so it is pretty clear he wasn't seriously plotting a revolution. Their interpretation of Jan 6 was wrong, partisan and material.
[0] https://blog.twitter.com/en_us/topics/company/2020/suspensio...
[1] https://twitter.com/bariweiss/status/1602364197194432515?cxt...