The (A)GPLv3 makes it clear that it permits all licensees to remove any additional terms that are "further restrictions" under the (A)GPLv3. It states, "[i]f the Program as you received it, or any part of it, contains a notice stating that it is governed by this License along with a term that is a further restriction, you may remove that term."
Interesting, and quite clear.
The whole response is very good, reasonable, and direct.
I'm interested to see what OnlyOffice will do. Maybe they'll relicense their whole product, leading to a community fork under AGPL.