This refers to physical impediments. Spreading legal information is not an impediment, it is free speech. If all info could be interpreted as impediments to federal officers then phones, the internet, the human voice, etc would be illegal
No, they are organizing legally, of course there will be bad actors, but blocking an agent out of bad faith is certainly less of a crime than a bad faith ICE agent killing someone for their assumptions
We already know that "doxxing" on its own is not a crime, and moreover that [non-undercover] federal agents are not entitled to keep their identities secret.
We also know that legal observation and making noise does not constitute interference.
So those may be their stated reasons, but they will not hold up in court.