I'm planning to release the source code of my bot (the best version I currently have, although very simple).
I'm glad, but curious as to what changed your mind!
After the release I will definitely not be able to get >50% anymore and guarantee the security of moto, so it will be up to community.
As well it should be!
Although you are correct that this would be a delicate and critical transition, I really do believe that it is for the best in the long run.
To ensure minimal safety of this process I want at least 5 people to write here that they are ready to mine moto 24/7 at least for the first two weeks.
I think you mean minimal risk?

Yes, we will want the hash-rate to distribute as much as possible quite quickly. However, I am confident that the community will handle it well.
HMC, can you insert my solver into your bot and compile it for Windows and Linux? I can give you a function that just tries to solve a level with specific nonce.
Then, I think you could make password-protected archive with all that stuff, upload it and reveal the password at some specific date and time.
Yes, this sounds quite reasonable to me. Ideally, we would also want to get a few people to again do the gitian build dance. We could release the protected archive of binaries together with the modified source, and announce the build hash in advance of the password. Then at the pre-disclosed time we would release the password, unlocking both the bot and it's source, and users could confirm the build. At this time we would probably also want to merge the bot into the reference client on github.
Are there any volunteers to be ready to do a build, as well?