It can be blocked, but doing so will block google.com. Basically Open Whisper Systems is making a block that much more costly to implement, since Google is ubiquitous in so many different areas.
If they can ramp up their homegrown options or a regional competitor to Google develops that can really compete well, why wouldn't they block all of Google.com? In China, it's already happening. It's completely possible because a lot of the population doesn't require access to English content, and so doesn't require an English search engine. Local search engines like Baidu and foreign search engines willing to comply with their local laws like Bing will be totally fine. And given that the Middle East has a lot of locals who don't actually speak English, I see that as a distinct possibility in the future. The comparison is almost perfect, no?
You're missing the point. Domain fronting is intended to mask the Signal traffic into something that's not.
Sure, they can block Google. Signal can do the same process with YouTube, or GMail, or whatever, and they can play a cat and mouse game like that until Egyptian people get really pissed off.
This comment explains better than I can as to why that doesn't matter. https://news.ycombinator.com/item?id=13268819 Essentially, if a local regional player (or a foreign player who complies with their laws) can compete to take the place of whatever domain they block, why can't they block any or all domains used for domain fronting? The cat and mouse game becomes irrelevant if local companies become relevant.
If they can ramp up their homegrown options or a regional competitor to Google develops that can really compete well, why wouldn't they block all of Google.com? In China, it's already happening. It's completely possible because a lot of the population doesn't require access to English content, and so doesn't require an English search engine. Local search engines like Baidu and foreign search engines willing to comply with their local laws like Bing will be totally fine. And given that the Middle East has a lot of locals who don't actually speak English, I see that as a distinct possibility in the future. The comparison is almost perfect, no?