A primary function of Freedom Of Speech is to protect the people's right to criticize their government.
No, that's Freedom of the Press. Freedom of Speech is the right of people to express the unpopular and even hated expression.
Now imagine, that a government (or one of its individual agents) broadcast loud booing OVER the soundtrack of any media it found critical.
This would be de facto censorship, not free speech.
No it wouldn't, it would be someone broadcasting booing over someone else's broadcast, even if they tried to 'de facto' censored it, it would be no different than someone broadcasting Porn with God Is Watching text flyovers in attempt at "censoring" that porno since anyone can ignore the booing and get the original broadcast, same with the porno. Let's say for the idiotic thought exercise that there is no original as they have all the copies, then I'd ask why broadcast in the first place, because censorship does not include broadcasting the only version with loud booing over the top, EVER (including such an idiotic hypothetical).
The point of this hypothetical is to place the government in the position of the SJW.
(IFF) it's ok for an SJW to air-horn Ben Shapiro in person (THEN) it's ok for a government (or corporation) to air-horn anti-government speakers.
Interesting side-note. There has been some research into speech-jamming technology which could be used to silence speakers at large rallies (like Martin Luther King jr. for example) and it has the added bonus of making the speaker look like an idiot (potentially destroying their credibility).