That's why bonus torrents are excluded. If there's a lack of seeders, then it will allow seeding no matter the ratio. Maybe loosen the restriction on what's a bonus too. Because those who seed just one torrent, other than the one they are leeching is partially the cause of the problem.
Small torrents also excluded because they need a constant seeder to keep alive....though becoming a bonus helps.
A 5.0 ratio is quite generous, imo.
I've got 5.0 on more than 21 torrents, and I never seeded JUST one at a time to manage it. Any restriction is an arbitrary number that doesn't factor a very important consideration: time. It's easy to get 5.0 given enough time. Take a look at houkounchi's profile, he's got bonus torrents, that, because he can seed so many things at once, have been seeded several dozen times over since he can keep them all going. So you would suggest he turn those off, so some other guy could come in? I guarantee the swarm suffers if users like him drop a torrent as soon as they hit 5.0.
Your plan assumes that all torrents are worth treating like they're uber popular, and that some Little Timmy with a broken ratio will come in and take over, if only some mean user wasn't hogging all the leechers. Instead your plan discourages long-term seeding. It also requires two users to take action for one to benefit, and you're coercing one of them by punishing them for seeding. If a torrent is low interest, more likely you're just discouraging people from seeding them at all. You can't make users download something.
No, the bigger problem is a lack of leechers, which your plan doesn't fix. The solution is really to not rely on just one torrent to reseed. From personal experience it's much easier to saturate your upload by have more than one torrent to work with. Some torrents have no leechers, and you have to eat the ratio. But that doesn't mean things would be better if you started removing all the high ratio seeders from the equation.
With all that being said. It is still a problem for people being unable to seed. Even if my solution definitely has it's faults.
You say it's due to lack of leechers? Well, these new leechers are going to get a hell of surprise downloading that Houkunouchi/seed boxed torrent. While they may enjoy that fast downstream, they'll quickly find themselves in a deficit that may take forever to recover uploading on that torrent and getting banned while waiting.
How is this inviting to new leechers?
I think some of you forgot what it's like to first start out on a private tracker.
GAH, I'm just going to straight up and say it since I care

For all those finding themselves in a hole and only being able to seed:
Find a torrent that you like that has a low seed ratio.
Bookmark that page (not the link).
Log out of BakaBT.
Go back to that page and download the torrent without the passkey.
Download the files, and if you are honest, seed to 1:1 ratio.
Log back in BakaBT.
Go back to that page and get the torrent with the passkey.
Now use those same files to seed that torrent and get your ratio back up.
Stay away from well seeded files for awhile. I know that's most of the favorites, but will cause less anxiety till you build up a good seed ratio.
btw, if we go back to being named BoxTorrents, will be easier to find

The old site no longer links us to BakaBT. So for now, it's even harder to get new leechers. If keeping the name, someone can at least mention the transition on other forums.... but that may spark other debates :/