Putin is popular. This story is not big in Russia. Even online (where the state doesn't control the media) it's not a big story. They have an election now, and we have no other news currently. There is no opposition, but a lot of people genuinely love Putin. He's strong, he stands up for Russia, and he brought a form a stability to Russia when it was in a state of semi chaos; with Oligarchs and mafia doing as they pleased. That is still going on, but you have to be part of the Putin elite to get a slice. Its controlled. Its not anarchy. When Putin came to power he got all the Oligarchs together and told them not to get involved in politics or use politics to further their businesses. Some ignored him and landed in jain with corruption charges. Where Putin hasn't done well is investing as much into education, instead Russia spends a monstrous amount on arms and military development.
I don't think this spy poisoning is about sphere of influence. The spy was providing info to various agencies on Russian secret service details. He was publicly dealt with to stop others doing the same. Syria is not a game to Russia, they have lost many lives and spent billions, but sphere of influence comes into it. The Asad family regime has always been an ally going back many decades. Russia also has a Islamist problem itself with Chechens etc and I think the greatest number of foreign ISIS fighters came from Russia or ex-USSR so controlling ISIS was important to them.
More or less everyone in our foreign office and around the world knew that the most sensible way to deal with Syria, when people were protesting and ISIS were growing, was to work with Asad. Not only have we seen what regime change has done to Libya (lawlessness, civil war between rival freedom fighter groups and more destruction) Asad was actually a relatively decent guy pre-barrel bombs. Trained as a dentist in the UK, he was progressive and modern. He never really wanted to be King. Russia's plan to work with the existing regime and reach stability was a logical one, one that the west understood too. If others were not funding the opposition, it would have been simple to stabilise the country and get rid of ISIS. The problem was others didn't like the Syrian regime. They were too close to anti-israel groups etc etc etc. The amount of money pumped into various armed groups in Syria by different nations is astonishing.
This diagram shows just how many outside influences were fuking with Syria trying to influence geo-politics. The people of Syria are the losers. Yet, you could argue that without Russia helping to take control, a worse civil war might of raged for many years,
as is the case in Libya.