Dewatering a toilet with a shop vac

[Hackney plumbing]

quote; Usually when all the waters gone I turn my vac off and stuff a rag into the bowl. Yank the toilet up and stuff the same rag into the flange.

Then do you remove it and stick it back into the toilet before you reinstall the bowl or its replacement? You may have a compulsive disorder, to worry about any errant odors to that extent. I drain the toilet, remove it, install the new one, then discard the old one.
Methane, or any other gas, can only "explode" when it has the proper air/fuel mix, and your sewer does not come close to having that mixture. I use a soldering torch by open drains all the time, and in the old days we used oxy/acetylene cutting torches on the drain lines and NEVER blew one up, or even start a fire. The "hazard" is grossly over sensationalized.

No I have common sense not to breathe some strong sewer gas....so I use prevenative measures. My issue if you read my post has nothing to do with an explosion. Some areas have heavy sewer gas such as building near large sewer mains or near industrial areas. These sewers under heavy flow push alot of gas out. I also put the rag into the pipe to keep anything from falling into the pipe as I work.