I assume there would have been problems in leaving HK undefended, so there would have been significant risks.
That said I think the British suffered from being far too spread out, to the extent that they were not really strong enough anywhere to achieve any success. Making Malaya strong enough to hold probably required most of the HK garrison, more modern equipment and better training for those stationed in Malaya, Matilda II tanks and a better air defense in terms of more and better organization. Arguably the resources were available, but it would have required taking more from the UK and likely a bit less Lend Lease to Russia (which would have had consequences).
The fleet also needed to remain intact for longer, to prevent landings further south on the coast of Malaya.
Leadership needed to be different, Percival and the RAF head proved unsuited to the role.