You may be interested in a similar (lengthy) thread on overlapping ideas http://gov.yearn.fi/t/gyfi-time-weighted-voting-power-distribution/
While it would be unfortunate for anyone to lose YFI, it would not affect quorum because those YFI were not part of the quorum calculation. Quorum is based on the number of YFI staked in the governance pool not the total number of YFI in existance.
We discussed the risk of a malicious actor borrowing YFI and prevailing on a system ending vote on the other thread as well. @Joey suggested that in the short-term even if a malicious actor prevailed on a vote, it would still require the actions of other to implement, and Andre or the multisig would refuse to implement. While not a good solution long-term, it makes me less fearful of such a takeover or catastrophic outcome – assuming Andre and the multisig are willing and able to go against the vote. Curious what those on this thread think about that.
Also consider what the real value of encouraging or forcing governance participation is when YFI holders choose to seek significantly higher yield elsewhere. Participating is important, but contributions can come in many forms – including work product, testing, ideas, and suggestions – and voting is just one way to participate.