Tbqh, the main reason for alot of people who have problems with races on various maps is due to the necklace of immunity rarely working in most cases and never working in others.
With regards to the nade barrel trick... its only "fun" and there are plenty of ways to stop it from killing you!
Buy more hp
Use a race which starts with more hp or one that can give via ulti!
Nade them back as u get switched.
Buy necklace (if its fixed)
Have some sense and actually "shoot" the barrels before they can be used! (as ct thats easy)
Use a race with invulnerability.
Also incase you hadent considered this but what your calling a glitch can happen on "any" map with a race that can switch places... Not just on crackhouse... So, if people really feel against this then best bet would be to remove races which can cause this "glitch"!
Thats my opinion anyways....