When making judgements there is following the letter of the law and then there is making equitable decisions, which takes into account both the letter of law and the context in which the decision is being made.
In our current environment, where a potential incoming chief executive of the USA is, according to some military leaders who worked closely with him, a fascist, the equitable decision is to have the lecture now.
The alternative is to wait until that chief executive may be in power, at which point pressure not to have the lecture will only increase.
If the lecturer in fact violates the hatch act, that can be dealt with when it happens. Even if it is a pain in the ass. Who said this was supposed to be easy?