Brochu (1996) concluded that crown group crocodylians have a caudal to cranial pattern of suture closure, not cranial to caudal as you state here. Likewise, Irmis (2007) observed the caudal to cranial pattern in phytosaurs.

Given that all your vertebrae preserved vertebrae are from the dorsal portion of the column and all have open sutures, I don't see how you can conclude one way or another the pattern of suture closure. Just because the specimen is larger than others from the same site does not mean it is more mature - plenty of authors have pointed out that size is not necessarily a good correlate of maturity, which is why Brinkman (1988 in JVP) and Brochu (1996), among others, emphasized the importance of "size-independent" maturity criteria.

Brochu (1996 and 1992 MS thesis) did indeed note that suture closure of the more cranial vertebrae was one of the last things to occur relative to other maturity indicators, similar to what was later observed by Ikejiri (2012). I think the lessons of Bailleul et al (2016) should certainly be taken to heart by vertebrate morphologists, but neither Brochu (1996) nor Irmis (2007) ever advocated that vertebral suture closure be the only method for determining maturity.