I think it is perfectly normal for him to not be acting sleepy before bed.... He is obviously tired as he drops straight to sleep with motion. I know my daughter is the same and will be having a little rave right to being put into bed! My son though, was not likethat and would always sit and have a cuddle before bed and 'chill out'.
The kids have bath at 6.15, abd then they have 'chill time' which is from after bath (about 6.40ish) to bedtime (7pm for dd 7.30 for ds) out chill time generally consists of us all sitting on the settee either reading books or watching Miles from tomorow (which finishes at 7) once that finishes DD knows its bedtime. DS will sit down with me and dh and cuddle up, read, chat. And always have been that way. DD though potters about, she will get some toys and be playing, she will
Pop upstairs for something, come back down, she wont sit still. Its just how she is! I guess its the spirited in her! Which reminds me of how you describe your DS. She seems to hype up more when she is tired.
That said, when its bedtime, its bedtime, and i simply say 'its bedtime' ask her to kiss her dad and brother, which she does. And she has a mad dash upstaird like she has a full day of energy in her. She has a wee then i put her in bed we have a kiss and a song, and i leave. She often sings to herself for 10/15 mins then is asleep.
What im trying to explain is, although he may not seem to be able to switch off, he IS tired and if you implement gradual withtdrawal i think you will crack the problem!