The problem I see isn't necessarily the rep requirement, but the fact that many high rep users are inactive. I am one of the Area 51 users on the top users page in Area 51, and I've looked at the profiles of all of the people who have more reputation than me. Most haven't had any activity in over a year.
5 trusted users should be enough to consistently help moderate Area 51 without turning it into an environment where there's too much moderation, but none of the trusted users are active. Two of them have at least a 10 reputation point gain in the past year, and the other three haven't had any gains in over a year.
None of them have asked any example questions or left any comments to help improve example questions. Only one of them has such activity in the past year, and in two weeks that will no longer be true.
These users are exceptional people and contributed a lot in the beginning to help many sites get off the ground, but somewhere along the way they lost interest in Area 51.
As an avid Area 51 user, I regularly drop comments where I see people need help, and I regularly use my editing privileges to help fix or reword proposal titles or example questions that might need a little boost to make them exceptional. These are the most important tools, and it only takes 1000 reputation to gain access to these features.
As for comments, at 101 reputation, anyone with Stack Exchange experience can help guide others by commenting and voting on example questions.
I also participate in voting to close or reopen proposals, and I do believe this is important. The more community participation in voting to close and reopen, the better the system scales. While we could use more active 2000 rep users with this privilege, artificially dropping the bar on this and trusted users may add more people to the mix who aren't yet knowledgeable enough to make the correct decisions as to when to close, when to delete, when to reopen, and when to undelete. Many times, the answer is to start a discussion, encouraging others to rethink the proposal definition or example questions so that the proposal thrives.
Instead of lowering the bar, perhaps another answer is to drive more participation in Area 51. Add links to proposals you support to your user profile. Encourage others to do the same. In chat, discuss proposals that are similar to sites you participate in that others may be interested in. Just be sure these are rooms you regularly participate in so you don't look like a spammer! :)
Hopefully, if we promote Area 51 more, those existing trusted users, and those who are close to becoming trusted users, may renew their interest in Area 51 and once again lend a hand with their expertise.