Well, that's the thing. That's not as stupid as you're trying to make it sound.
There IS Microsoft Defender on Linux because there's multiple products that Microsoft calls Defender. There's the product that ships in Windows for the consumer market, which is just the basic antivirus product that you probably think they're talking about. However, Microsoft's full endpoint protection software is also branded Defender, and there is a Linux version.
And while you might think that it's silly to run that on Linux, (a) your business is probably already licensed for it so will be cheap to add a client, (b) it's what their infrastructure is already using so it's minimal setup, and (c) having security software everywhere is critical simply for saving thousands of dollars in insurance costs. The software nearly pays for itself in reduced premiums at any company of any size even if it does nothing. With how catastrophic ransomware attacks and data breaches are, insurance companies now require annual environmental surveys for evaluating risks.
So you're trying to make this IT team sound stupid, but as someone in the industry I can't even tell from what you said if they are.
I'm not trying to say they were stupid. I'm explaining my lived experience where I needed a lightweight linux server for an internal app and it worked great until a 100% Windows-based IT team policy required that Defender be installed on it, after which it became extremely slow and crashed regularly due to Defender-related issues in the logs.
There IS Microsoft Defender on Linux because there's multiple products that Microsoft calls Defender. There's the product that ships in Windows for the consumer market, which is just the basic antivirus product that you probably think they're talking about. However, Microsoft's full endpoint protection software is also branded Defender, and there is a Linux version.
And while you might think that it's silly to run that on Linux, (a) your business is probably already licensed for it so will be cheap to add a client, (b) it's what their infrastructure is already using so it's minimal setup, and (c) having security software everywhere is critical simply for saving thousands of dollars in insurance costs. The software nearly pays for itself in reduced premiums at any company of any size even if it does nothing. With how catastrophic ransomware attacks and data breaches are, insurance companies now require annual environmental surveys for evaluating risks.
So you're trying to make this IT team sound stupid, but as someone in the industry I can't even tell from what you said if they are.