Earlier quoted context omitted.
AIUI, no. That package was added in Honeycomb (API level 12), whereas WhatsApp currently supports Gingerbread (API level 10). However, two API levels of compat. seems like a good trade to me in order to avoid an RCE.
How many millions of users would be excluded if they chose that path, and are their controlling shareholders okay with that reduction of active users?
Less than 0.3% of Android users globally use an incompatible API level. If we assume this applies equally to the WhatsApp userbase (and old-Android users are represented with the same proportion in the active monthly users figure) and use 0.3%, we have 2.8 million potentially impacted users. At the current rate of about 1M new users per day, it'd take two or three days for this small slice of the userbase to be replaced.
It would've been losing 0.0219% of their userbase to avoid an RCE that impacted 100%. Now, how much revenue did those users bring in? And how much has this announcement damaged facebook's share price?
[1] https://venturebeat.com/2015/08/27/three-quarters-of-whatsap...
[2] https://techcrunch.com/2018/01/31/whatsapp-hits-1-5-billion-...