Well that's a post chock full of supposition if ever I read one, if you're going to challenge statements use math/logic and facts as the basis of your argument. So basically, if we take you argument back to it's logical basis we shouldn't trust anything/anyone and what we perceive is reality may just be a fictional construct in our heads..? Great work pal.
1. Mathmatically speaking - achieving a 10% net
swing in any form of voting is very difficult to achieve through manipulation. If >10% net of a voting population vote for or against something then it's generally accepted as the consensus.
2. MNO participation is in line with that of general voting percentages in most western democracies. Some types of vote achieve higher participation rates than in others depending on how important the MNO operators perceive the vote to be to them. For example, I know UK residents that wouldn't vote in EU parliament elections but would vote in General Elections and voted in our EU membership referendum. So when you put your statement into context against other 'Governance models' I think Dash is doing fine and participation rates are within norms of what you would expect to see in any governance model.
3. A lot of cheap coins have been traded and distributed to the point where your argument around concentration of ownership of Dash isn't a statistically material issue. For sure there are likely to be a few 100,000+ holders of Dash but that's still not a statistically significant enough number of coins (voting rights) to determine and rig the system outright. https://chainz.cryptoid.info/dash/#!wallets
Bottom line - your supposition that the grants system is being rigged doesn't really hold water. Demonstrate to me that the system is being rigged and I'll believe you. When the facts change I change my mind. You have yet to present me with any facts/figures that demonstrably prove that the system is being rigged... Surely if it was, it wouldn't be hard to prove??