This is completely standard journalistic practice when reporting a quote on something that is currently contentious or unproven. For example, consider the two hypothetical headlines:
Activists decry police murder of protester
Activists decry police "murder" of protester
The first implies that the police murdering the protestor is an established fact. The second makes it clear that it is the activists who used the term "murder" rather than it being a non-contentious fact.
Activists decry police murder of protester
Activists decry police "murder" of protester
The first implies that the police murdering the protestor is an established fact. The second makes it clear that it is the activists who used the term "murder" rather than it being a non-contentious fact.