I think I understand what you're saying, and I'm in line with your logic. I can't say if it's true or not, but it seems likely that if Malaysia accepts 100 ETAs, then proportionally more will be likely to drop out, giving more spots to alternates, with priority going to those who originally applied to Malaysia. Most people I know who were alternates and got to countries ended up at the countries they originally applied for. I hope things work out for you! And that this helps/makes sense