Instead of a kneejerk emotion response, why not demonstrate some critical thinking skills? The US has a robust civil court system. If there was indeed a binding contract to this effect, then this supplier will be able to recover the funds from Twitter, plus damages, interest, and court costs. The fact that Musk has chosen to risk this substantially more costly outcome clearly indicates that he believes there's grounds to deny payment: perhaps the systems failed to meet performance specs, the invoices were price-padded, etc. We don' t know, because we're only hearing one side of the story.
Here's a hint: whenever you see an article like this that fails to report both sides ... there's likely more to the story than you're being told.
I used critical thinking skills. Twitter ordered hardware under their Master Purchase Agreement; Musk bought Twitter, and decided they'd just not pay for the hardware they'd already ordered. They stopped paying rent on various properties, quit paying colocation and datacenter fees (not cancelling service with them; just quit paying), and in this case decided to not pay for hardware they'd already ordered.
You're right, there is a robust civic court system, and this company is using it to sue for what they are owed.
And no, it doesn't indicate he believes there's grounds to deny payment -- the data centers, the colocation, it was just a matter of they decided they weren't going to use them any more, so instead of ending their service with them, they just quit paying. Obviously I can't say for 100% certainty that there wasn't some other reason.. but there's nothing to indicate that there is either.
In raw dollars and cents -- the company reportedly cancelled purchses of $40 million worth of the hardware, and managed to sell $19 million of it to other vendors. So Twitter is "only" on the hook for $61 million out of the $120 million in hardware (plus interest, legal fees, etc.) So if that's your only concern you can say Musk made the right decision, they've saved $59 million.
I still say it's a ridiculous way to conduct business. I realize some people (this is not at all uncommon in real estate) think it's perfectly fine to, rather than saying "We don't need this product or service any longer", to just not pay and let things settle out in court. But I can and do say it's a ridiculous way to conduct business.