Political - adj - Of, relating to, or dealing with the structure or affairs of government, politics, or the state.

I don't know if you really don't know the difference between being black and supporting the BLM movement, but there is a definite difference. A good quick measure is would a politician hold an opinion on it? For a specific example do you think Tim Scott (one of the black Republican Presidential Candidates) would wear a BLM face mask?

I will assume that you are arguing and good faith and genuinely don't see the difference, so here are a few contrasting examples:

Wearing a hat that says Veteran is a statement of fact, like wearing a hat with your college's logo. It is not inherently political or supporting any particular political ideal.

Wearing a VFW hat on the other hand, would be political. The VFW seeks to educated and change the opinions of legislators regarding veterans.

If a black person was wearing a hat that said I am Black. That would be a statement of fact and not inherently political or supporting any particular political ideal.

Wearing a BLM hat on the other hand would be political. The BLM organization and supporters of the BLM ideals seek to educate and change the opinions of legislators and the public regarding black people.

Without typing out the same comparisons again, cancer awareness and most charities would fall under political ideals also. They almost always seek to influence government legislation or funding.