In my opinion, and yes, we're stretching this conversation for barely any reason, a warning is something u can do in chat/voicechat, a voteslay is not a warning even if you for some unknown reason think that it is. That's just wrong.
If you voteslay people without making sure that they're afk/pretend to be afk beforehand, that's abuse. Why? Because there is no 3rd option. Either someone is afk, in which case you're allowed to voteslay them so they don't delay the round, or they pretend to be afk, in which case again, you can voteslay. There is no 3rd option! So if someone gets slayed without one of the two above being true, that's abuse.
To make this clear, let me give you some examples:
1.: You slay a player who is still at the start of the map and hasn't moved for most of the round. Voteslay is successful, he says nothing. JUSTIFIED SLAY
2.: Same situation, you slay him, then he starts complaining. Did you warn him in chat beforehand? Yes. Did he react? No. JUSTIFIED SLAY
3.: Same situation, he starts complaining. Did you warn him beforehand? Yes. Did he react? Yes, but he still hasn't moved and is delaying the round. JUSTIFIED SLAY
4.: Same situation, you slay him, he starts complaining. Did you warn him beforehand? No. UNJUSTIFIED SLAY
If you don't make sure, that the person is afk or is pretending to be afk beforehand, you're just assuming something and trying to slay people. You can't know if the 4th guy is sitting at his screen or not until you make sure.
It is a pretty big issue. I don't want donators to be able to call votes and then instantly cancel them when they could be just a little more careful to avoid this whole thing. Let me tell you what will happen. Some donators will try to scare a lot of people on the servers for 2€ by constantly starting and canceling votes.
That is my view on this, I don't agree with the attitude of pushing aside the worst case scenarios by saying "It won't happen that often". Like if the Team Fortress community wasn't full with trolls.