h2o2 will hurt your sample. It will slow the growth of the mycelium. It is used to treat the casing layer in dire cases of contamination but it ALSO hurts the mycelium.

If a contaminate is present it will be evident on the Agar, so cloning to agar gives you the opportunity to isolate mycelium growth AWAY from a contaminate. Using H2O2 will slow the growth of the mycelium because the mycelium needs time to recover from the H2O2 bath and ideally we would want the mycelium to out pace any contaminate in an agar dish.

If an H2O2 bath were a guarantee of sterility than we would probably clone by just doing an H2O2 bath and then go directly to LC . . . of course doing that would just get you a dirty LC so instead Common Practice is Agar Work to guarantee clean clones.

I'm sure a lot of people do okay using H2O2 . . . but it just slows things down and if too much is used you just killed your grow. Read up on Agar and do some isolating.

OR you could attempt a LC in a glove box. Don't cut your sample out of the fruit body outside the glove box and be as sterile as possible.