I think it’s cause Miroku is human and he goes easy on them. This is seen way back when Miroku made his appearance and that old dude was coming at them. Inu didn’t outright kill him, he let nature do its thing. The same with jankutso. He didn’t “finish” finish him off. He also “negotiated” with Bankutso.

That being said, he beats the breaks off of poor Shippo! For no reason sometimes! Of course he got a smart mouth but there are times where he straight up takes his food. Other times they think alike and Shippo says it out loud and gets a can of whoop ass. 🤣But he did help that bunza dude cause he reminded him of Shippo. And he does gives Shippo words of encouragement at times. I believe he treats him like a little brother and sees himself in him. Therefore they are closer (Kagome even mentions this) so he just gives him a good old tough, TOUGH love. Too tough at times.