If it's already cycled, why are you adding filter media from other tanks?
Also- the 2215 shouldn't be an issue to tear apart. I opened my 2217 after it had been running for a week or so, to add some purigen, and didn't have any problem with it. It took me about 30 seconds to restart. I actually backflushed it out, and was AMAZED at the amount of crud in it after only a week. I restarted it, it spit some air out and ran a bit loud, i unplugged it & gave it a little shake to help work some air loose, and plugged it back in and it's running perfectly fine. If you have the quick disconnect valves, it shouldn't be an issue at all to get it started up again.
But, I agree with Chompers- squeeze it out into the tank, then drop it in the HOB. Even if the HOB is primarily for mechanical, if you can get it seeded with bacteria now, it'll help a cycle along. And, you can't pick what in the tank does and doesn't grow BB- it's on EVERYTHING. You'll find it on gravel, decorations, driftwood, glass, and every bit of filter touching water (including the insides of your inflow & outflow tubes). So, there's going to be BB in your HOB either way, and every time you clean it, you are going to kill some BB. Providing enough other places for BB to grow should be enough that it shouldn't make much of an impact on anything, though.