They don't even need to suppress it forever. They only need to suppress it long enough that it's not secure anymore because other tech can crack it, provably.
Then it's useless.
Again, they can probably already crack it (21e8) but they can't reveal that openly, publicly, to a large audience, because it reveals capability beyond what most people believe is possible.
I'd wager to guess that in the future there will be a public incident where Bitcoin is cracked, everyone knows it's been cracked, and the market collapses.