Nonsense, he is contrarian for the sake of being contrarian, completely misrepresenting the Porton Down event for political gain. Porton down claimed:

"It is our job to provide the scientific evidence of what this particular nerve agent is, we identified that it is from this particular family and that it is a military grade, but it is not our job to say where it was manufactured."

The evidence was handing to British intelligence which did conclude that, however. Boris misspoke and wrongly attributed the conclusion to Porton Down and Corbyn and the Russian social media influence jumped on that.

Not only that, but to contrast Boris, he condemned any hostile actions against Russia saying it wasn't the time for that and that we can't condemn Russia, that he would still be open to business with them after the attack.

Of course, after the severe backlash, he *completely backpedaled stating:

The evidence points towards Russia on this, therefore responsibility must be borne by those that made the weapon, those that brought the weapon into the country and those that used the weapon

Look, if you want to play contrarian to the government for political points, great, but don't do so blindly and play into being a useful idiot to Russian in the process. Lost a ton of respect at that point.