Can I use Polearm master's bonus attack if attack with a quarterstaff and an unarmed strike(Extra attack)?

Question

I play a level 5 Monk Kensei/level 1 Druid, have a Polearm master feat, with Shillelagh spell.

I try to Extra attack(Monk feature) with a quarter staff and an unarmed strike, then do a bonus end weapon attack from quarter staff(Polearm master feat).

The reason I try to add an unarmed strike in the Attack action but not bonus action because Monk Kensei 3rd level feature:

Agile Parry: If you make an unarmed strike as part of the Attack action on your turn and are holding a kensei weapon, you can use it to defend yourself if it is a melee weapon. You gain a +2 bonus to AC until the start of your next turn, while the weapon is in your hand and you aren't incapacitated.

But my DM does not allow me to do the bonus action with Polearm master feat because Polearm master feat said:

When you take the Attack action and attack with only a glaive, halberd, or quarterstaff, you can use a bonus action to make a melee attack with the opposite end of the weapon. This attack uses the same ability modifier as the primary weapon.

He insist on the word only in the Polearm master feat, and do not allow me to have the bonus attack from quarterstaff in this situation. But I think in reality add an unarmed strike in a sequence of attack with your quarterstaff shouldn't be a problem.

What do you guys think about this?

Answer 1

DM has final say.

Your DM has final say in how the rules read. If he wants to say "only" is that important, then it is that important. However you do have the option to make an unarmed bonus attack and use Agile Parry if the AC boost is more important than attacking again with your Polearm Master feat.

Martial Arts Says :

When you use the Attack action with an unarmed strike or a monk weapon on your turn, you can make one unarmed strike as a bonus action. For example, if you take the Attack action and attack with a quarterstaff, you can also make an unarmed strike as a bonus action, assuming you haven’t already taken a bonus action this turn.

(emphasis mine)

Answer 2

By RAW, your DM is correct.

By attacking with an unarmed strike during the Attack action, you are not fulfilling the requirements of the Polearm Master feat by attacking with only a glaive, halberd, or quarterstaff. Therefore, the resultant benefit for that feat does not occur. According to the rules, attempting to gain both the +2 AC benefit from Agile Parry and the bonus attack from Polearm Master does not work.

By RAI, it's up to DM interpretation.

There has been no errata or Sage Advice about this that I can find. As the Way of the Kensei is from Xanathar's Guide and has been through two previous UA revisions, this is undoubtedly one of the areas where things that don't mesh would have been changed, yet the wording on Agile Parry remains the same.

As such, if you wish for things that don't officially combine in RAW to work in a campaign, your DM should make a ruling, and it appears they have done so.