ILR and HSMP dependent over 18

[RSARD]

My son was 14 when we came to UK on WP. He was WP dependent and ina year time I switched over to HSMP with him being HSMP dependent. Total combined (WP+HSMP) period is now 4 years but now my son has crossed 18 yrs. I am not yet sure whether I apply for ILR now or after 5 years but

Interestingly I came across one of the statements in AIT ILR judgement case which I have reproduced below :

The decision is
not in my view unlawful in respect of the third appellant because the HSMP Guidance did
make it clear that children who reached the age of 18 whilst in the UK would not be entitled
to settlement after four years along with their parents and minor dependants.

This means that children who are 18 yrs age or more as HSMP dependent at the time of ILR application are not entitled to ILR along with parents after 4 years.

Am I right in my understanding.