If IM would be solving a problem, I would agree. Unfortunately it is crapware. Crap. Ware. It is not solving a problem. It is making the world a worse place. Maybe they should start Investing into viruses?! where does this end? It's something I wouldn't expect of pg and yc. It's simply immoral and shit behaviour. Divest or be disgraced!
Classic straw man argument. Viruses are illegal in almost every case and thus clearly they should not, and will not, invest in viruses. Not that I support IM, but they are solving a clear and distinct problem: software is hard to monetize.
I'm not sure why you characterise this as a straw man argument. GP post suggests that investing in viruses is unethical on a similar scale to investing in deceptive crapware installers.
You drew a separate distinction between those scenarios (whether or not there is a legal difference between deceptively installing crapware and promulgating viruses). I would suggest that you are re-stating and seriously misrepresenting GP's argument, rather than pointing out any genuine fault with that argument.
On a related note, in my view tying your ethical standards to whether or not a given activity is currently illegal is both lazy and far from optimal.
The virus statement was a rethorical question..
Unfortunately it is not a real problem that users face. It's a problem that a very small minority has and that inconveniences the majority. If that's what you set out to do in life..