Orange is strongly associated with Bitcoin and Bitcoin Cash.
Regardless of public opinion, Bitcoin BCH is an upgrade of the Bitcoin protocol. Bitcoin BTC is a fork that refused to upgrade and has introduced new consensus rules.
Bitcoin BTC has persisted because they refused to remove the 1MB limit, they are in my opinion less bitcoin than Bitcoin cash as they have changed the original consensus rules, removing signatures from the blockchain, the result is only implementations following Core's definition of Consensus Rules can see the bitcoin transaction signatures.
Our job as BU is to communicate our intentions, and have a visual identity that makes it easy to recognize the reputation we create as an organization.
There are technical reasons to differentiate to prevent accidental sending has been addressed with the
cashaddr, I included the link to refer to Bitcoin' Cash's Corporate identity colour Orange. One aptly chosen to lead and maintain consistency with the history while still being distinct and true to the original brand identity. It is a good design and should not be overridden by ignorance or the will to brand BCH as an altcoin.
Bitcoin Unlimited has a Brand too, our brand should not change with the whim of developers who thinks it's cool, or some random proclamation that green is better than orange or the unquantifiable notion that there is "overwhelming consensus" for green or heaven forbid it's too much work. Brand identity is not dictated by public opinion, and it should not be changed unless you are averting a public relations nightmare. e.g.
Monsanto
A Brand Identity is about consistent visual communication. BU's Brand has nothing to do with the Bitcoin Cash's bikeshedding green or orange debate.
We have or should have a consistent visual identity across all projects and visual identifiers undertaken by the BU organization.