It is a choice that is going to cost his company money. Talented potential employees are going to be well aware of the potential to be fired without a second thought(or severance) on the whim of Elon from now on. Twitter will have to increase compensation or settle for less talented individuals to balance that potential. That is where he does not "get a pass".
I agree of course from a human social standpoint that it would be moral and appropriate to give as much notice and severance as possible. However, there are many factors that come into play when making decisions of this nature. I do not know the full compensation package of the employees(were they already overcompensated?) or the total financial status of the company. The company could in theory be on the brink of failure. If Elon gave the fired employees a sweet parting deal and the company subsequently goes broke, leading to even more layoffs that would be terrible for the remaining employees. Furthermore, what of the employees that have to be fired or never hired in order to compensate the employees that are already leaving? I wonder how the vote would go from the employees if a company proposed the following:
"Would you rather we fire without severance pay 100 employees tomorrow or fire 150 with severance pay next month?" That's essentially the question that happens in management when a layoff is happening. Sadly many people fail to see that 50 jobs were saved in the first scenario when they read headlines about layoffs.
Either way we think, the complexities of human interactions in the markets and business is fascinating!