Copyright and trademarks are two different things. Anyone who conflates the two and claims familiarity with the law should be suspect. Copyright is automatic, but I don’t believe trademarks are in the same manner.
IANAL, but in my previous research, claiming a trademark through the use of “TM” common-law mark will get you some limited rights in the US, with much stronger rights for those marks that have been registered. I’m sure the LE legal council will give good advice on how to get things straightened out, although it’s sad that time is having to be wasted on fighting what seems a bad-faith effort to create confusion and/or disadvantage a competitor.