Welcome to the community, and thanks for your thoughts on this issue.
The higher the voting rewards for a specific topic, the higher the financial incentive to spam that topic. This issue only exists because governance followees were split from the rest of followees earlier this year.
Creating a neuron is very inexpensive. If I were the spammer (and making over 1k ICP/month from spamming), then I would just create tens or hundreds of neurons and rotate through them for each proposal depending on the cooldown.
I would also recommend looking at this post for some recent context on prioritizing the implementation of 55651, which would boost rewards for active participants. Proposal to Prioritize 55651 (Periodic Confirmation) & 38985 (Manual Voting) over 48623 (Compounding Maturity)
as well as this comment,
Arguably votes on updating the replica (code) are even more important than the governance votes. The more I think about this the less it makes sense to boost rewards for votes on the governance topic.