The plug-in that prevents users from joining BLU unless their microphone is used is very faulty from my experience, as it solely checks if you use a mic, not if it's actually quality/sufficient (i.e, if you press Push-to-talk for a second, it'll validate you joining BLU). I wouldn't trust it to prevent users with no mic or an insufficient one to join BLU, neither would it really fit for our servers given users with no mic can join BLU if the team is in need of filling.
However, an improved plug-in that prevents users from joining BLU without a sufficient mic if the team doesn't need additional users could be helpful. Although, that wouldn't solve existing guards blocking users with a mic, but perhaps priority could be given to users who've proven to have a mic over users without one when teams are auto balanced at round beginnings.