The nature of something like this is that the cost to run it naturally goes down over time. Old links get clicked less so the hardware costs would be basically nothing.
As for the actual software security, it's a URL shortener. They could rewrite the entire thing in almost no time with just a single dev. Especially since it's strictly hosting static links at this point.
It probably took them more time and money to find inactive links than it'd take to keep the entire thing running for a couple of years.
The nature of something like this is that the cost to run it naturally goes down over time. Old links get clicked less so the hardware costs would be basically nothing.
As for the actual software security, it's a URL shortener. They could rewrite the entire thing in almost no time with just a single dev. Especially since it's strictly hosting static links at this point.
It probably took them more time and money to find inactive links than it'd take to keep the entire thing running for a couple of years.