Yeah I gotta say personally both sentences sound violent to me. They can absolutely be understood in both a violent and a window-smashing way, but the wording is so on the line that I too wouldn't want to see it in a community.

The meaning of what we say or write is not purely what is meant by the speaker/writer but also in large part what the audience or the person we speak to hears and understands. As the person saying something, we always have to be aware of how it may be understood or misunderstood. We all have different contexts, experiences and ways of communicating. All we can do is be as specific as possible to remove any uncertainty. Vague wording is how dog-whistling operates.

Maybe a better way of wording it would have been:

"if people start flying (...) flags on their cars in my country, they better watch out for their windows 'cause I'll be keeping a baseball bat in my car"