Well there's nothing prohibiting that from the aircraft point of view... not uncommon to do that in the A320. Good fun, and the FMGC handles it just fine.
However - are there limitations for the company? in which case speak up and say that it's not permitted. (Many companies have speed gates that incidentally seem to cause more problems than they solve)
If not - is the FO feeling out of the loop through inexperience - maybe saying "I've never seen this done before Captain, can you talk me through what you're doing and why?" to keep up with the aircraft and the skipper? After all, the decel point is there to keep you out of embarrassment (provided you are in managed speed!).