Should be be starting kindergarten this year?

My son turns 5 in august. My ex texted me (not his dad) if he was starting kindergarten this year, because his son (who is the same age as my son, just a month apart) is starting kindergarten this year.

My son has speak delay so I was like ok well he will just start next year when he turns 6.

Is this right? he doesn’t seem ready at all for kindergarten. He can’t really even communicate 100% yet.

He also made it a point to tell me that his son can spell his name and that he’s getting super smart. Not exactly sure why he felt the need to tell me this? While we were together he constantly compared the two kids and it was annoying.