Just quick search on google and I found this
Quote from: https://onlinetrademarkattorneys.com/blockchain-bitcoin-trademark/[/url
No one can claim they own the term BITCOIN. As a result, everyone can use it, even in their own trademarks.
But the way it seems no other project or business can use that term "Bitcoin" because it looks like already a trademark for btc, even though not official, it will be very weird for another brand to use now, everyone is already aware of bitcoin and btc as its ticker,
I don't think it is appropriate for anyone to use it now, just my opinion.
.
. 
