It is both, but Mozilla has never tried to hide it. Read their blog for a bit and you'll see ton of advocacy for various subjects.
Cherry-picking expenses that total barely 500k out of a 500M budget and hiding it behind "noooo we don't get political here promised" is also pushing an agenda.
The Mozilla Foundation does plenty of stupid shit. I don't agree with much of what they're doing, starting from Baker's insane pay for how terrible of a job she does. But 400k to an association... At best that pays for two rallies that total 500 people, at worst it's giving money to friends.