For some reason most people refuse to accept the reality of bioweaponry (unless Iran is supposedly using them). The same thing happened throughout the UK-EU referendum; you could literally show people explicit, public statements made by EU statesmen about the necessity and imminence of bloc-wide military capabilities... but Remainers would insist it is nothing but conspiracy theory. Similarly, you can point people to any number of laboratories, experiments, manufacturing chains, official policies, and even scandals evidencing the simple reality of bioweaponry and people will overwhelmingly dismiss it. Even those that do accept the reality will, however, always assume good will.
The overwhelming incentive for politicians is to coverup not just their own but other countries' use of bio or chemical weaponry in the interest of maintaining gainful international relations. After all, it is only very bad regimes that use them, and we immediately target these regimes directly (often with the explicit aim of annihilating their weapons capabilities). Good governments never use bio or chemical weaponry except in the most extreme circumstances whereupon they always manage to find such weaponry readily available and are quite prepared to use it - even though it contravenes international agreements and convention going back over a hundred years now.