It's impossible to keep up with the posting activity but I hope this question doesn't get lost.

I'm curious about the instructions to move all BTC to a new wallet. Is this simply a way to ensure
BTC and BCC don't use identical keys going forward or is there a technical reason for it?

I ask because if users do nothing they are in that situation already. They have BCH that can be accessed
by their BTC keys imported into a BCH wallet. If BTC need be moved in order to claim the BCH shouldn't that be
the case also if abandoning the BCH. After all it still exists.

If there is no technical need to move BTC to a new wallet with new keys the only issue is the existance
of two currency wallets sharing the same keys. Since I own the keys to both what is the security risk?

Edit: changed BCC to BCH.

One additional point. If the BCH is claimed as described in the OP wouldn't the old BTC wallet still exist
and be useablewith the original keys?

Ok another point. The original keys are associated with the same addresses on both currencies. IF BCH keeps
the original keys it will also keep the original addresses from the BTC wallet. It might be desireable to keep
your existing BTC addresses as BTC addresses and obtain a set of new addresses for BCH. To that end would
the following process achieve that result?

1. Create a temporary BCH wallet using the existing BTC keys.

2. Create a new permanent BCH wallet with new keys.

3. Move the BCH from the temporary wallet to the permanent wallet. The temporary wallet can then be discarded.

4. Continue to use BTC with the original keys.