The opposition protesting here is 1/5 of the population of the country . Its basically all people.
Like 1 million protesting in a country of 5 million , is all voters between 18- 59. Russia is loosing , the rot of oligarchy is dissolving.
That's 1 out of 4 working age citizens hitting the streets - not all people, but a huge chunk. It's safe to say there are going to be a lot of sympathizers in the non-protesters, a lot of people who wanted to protest but couldn't. There are definitely those who support the government, but I'd wager they're less than 15% of the total population, with the rest in opposition, or at least not in support of the government.
The usual tipping point for revolution is lower - if 10-12% hits the streets, it's a strong signal that the movement behind that activity is taking power.
According to that graph the cohorts with age less than 15 and more than 69 form only 27.7% of the total. Parent was broadly correct.