This is an artifical distinction. Take, for example, Sea Sparrow. This started out as PDMS, but it is widely regarded 'a proper SAM'. You also need to be specific at what you consider 'a proper SAM'.
https://en.wikipedia.org/wiki/RIM-7_Sea_Sparrow#Point_defense_missile_system_.28PDMS.29
The term SAM just means surface to air missile. Like the terms CIWS, Point Defence MIssile System is misunderstood. Point defence just means "active protection of a single asset". As opposed to e.g. Area Air Defence, which includes - in the naval setting - consort ship protection i.e. long(er) range coverage. Any ship mounted SAM is in essence a PDMS, just some can also provide AAW due to longer range. Here, one should consider that the range of the newer ESSM aproaches that of the older SM1MR. The former is a PDMS (which AAW covered by SM2MR and SM6), while the latter was an AAW asset.
In both RFPs there is a requirement for a SAM with AMD capability. There is no specific requirement for a long range system but one RFP leaves open the possibility of a longer range SAM while the other more explicitly limits the SAM to self-defence. Personally, I don't see a need for anything with more range than ESSM on a corvette, since this also mean a step up in sensors and hence cost. There is no difference in sensor requirements between the RFPs to suggest that one would have a longer range SAM. From the point of view of production, maintenance and logistics, it would actually make sense to have common systems (greater production volume > lower cost; ease of maintenance > lower cost, unified operator training > lower cost).