Well, this idea should be scrapped, games like CoD put it in well, but this isn't CoD, it's TNT Wars and all should be reasonably fair.
Less than half of all new guests don't go to the tutorial and if this was to be added, problems would arise. For one, I know of a few servers with the /fly command that lag real bad. This may do the same. Two, guests get angry enough when I kill them twice, being invincible and a good player would get them seriously enraged.
I have put this out there, and I don't personally think this will work.