Sheathing/unsheathing weapons to cast spells

Question

My friend is playing as a cleric that uses a shield in combat. I am unsure of how the rules for sheathing/dropping weapons work. The way my friend is playing, he seems to be able to cast a spell and use a weapon attack on the same turn, but this feels wrong to me.

Is this loop allowed in the rules:

Combat starts: Uses action to attack and then sheathes/drops weapon (using free object interaction) Uses bonus action to cast spell with somatic component

2nd round: Uses bonus action to cast spell again, Uses action to draw/pick up weapon and attack.

Repeat.

Using this loop, the cleric can always cast a somatic spell (provided it is a bonus action), attack with a weapon, and benefit from shield AC every round of the combat. Is this right? Being able to draw/sheathe a weapon for free each turn seems to make the warcaster feat pointless (save for concentration buff)

Answer 1

A cleric's holy symbol may be borne on their shield, allowing them to use it as a spellcasting focus. As a result, they can cast V, M or V, S, M spells with a weapon in their other hand without any difficulty or juggling at all, but V, S spells would require a free hand.

The loop you've described would work, yes. You give up attacks of opportunity during the turn off, though, and you can't do other object interactions.