If service time were not a concern, I'd still be 50/50 about wanting him to break camp with the big league team and a lot would depend on what we saw from him in ST.
In 2018, he started off the year at Charlotte and he really wasn't ready - he had major control issues, topped off by a performance in mid June where he walked 8 batters in 3 innings. This wasn't just him working on something, it literally took him April, May, and June of that year for him to figure out how to control anything he was throwing. Once he figured something out, in early-July, he put together a run of 7 starts where he walked 4 people total the entire time.
If he's throwing in the spring and his control is that pinpoint, then yes you can say he's "no doubt one of their 5 best SP". But we saw the same sort of control development for him in 2017 and 2018 both, where it takes him until May or June for him to find his control, then he would simply not be ready. So it's not just service time, it's not just the innings limit or protecting him physically, we have seen him need a long time to find control before and until we see him in games throughout March we don't know where his control is this year.