Well I'll take a stab at this.. As a suggestion I would cut some of the bamboo and then let it dry, or cure. Long enough to resemble something that does not have any green to it..
I am not sure how long this will take? Hopefully not all that long. I do agree with your concerns about the fear, and possibility of it sprouting and growing in the garden., For better advice I think you should perhaps post a question to the bamboo forum??

I think they would definitely have better information in the regards to it sprouting or the chance of it taking off on you in the garden.....

Also I have seen some neat video's on youtube with the regards to using bamboo as a trellis, and how to do it... I would check that out as well... i.e. just a general search of how to make a bamboo trellis should pop something up? I hope this might help with your dilemma. I have used, and still do use bamboo for trellis's for my tomatoes, and other such gardening projects. It is really great stuff! Makes me tempted to plant some just to have an endless supply however, I don't want a forest of it either.

Hope my suggestions help to point you in better direction.. I'm not very good at describing construction projects. However, I've found it very helpful, to watch someone else do it via video... such as on youtube and such.

happy gardening!
bgrow_gardens