Re: I'm getting stabbed...
I fell into your line of thinking about the offence of retaliation for a while but then I realised.
They call up saying you have a nasty thing on your computer and yes you have so you say
"Yes I have."
They log into your computer and the nasty thing turns round and bites them. You have been totally honest, they called you, they got the problem, where is the issue?
To take another example, you call a repair person saying that some electrical device is faulty. They come round and either collect it to test at their workshop or plug it in with you.
It goes bang and they get a shock.
You are dealing with 'experts who know about these things' they should fully understand the risks of faulty electrical devices or bug ridden PCs - that is their job, not yours.
[Word to the wise, just in case, do not let a gas fitter test for leaks with a lighted match.]