As Frank and the team do also. Coach the team to win (or not lose). Play football to win (or not lose). At the moment, neither of these conditions are being met either.You're a supporter mate, you literally have one job.
Understand you don't like the football and pay big money to watch turgid shit but booing your own and targetting is just shit
By definition you're not a supporter because you're not doing your basic job as a fan which is support hence the term so Frank is well within his rights to say that.
By your own metric, Frank and the team aren't doing their basic job since I'm sure the goal isn't to lose games so we're well within our rights to be discontent. Booing invididuals isn't something I would do, but don't care if others do. I wouldn't call them a lesser fan or supporter.