Speaking for myself -- not Bigtop:
For 1.2.1 this will not work since there were several issues triggered by aarch64 .
Off the top of the head: Tez, hbase -- maybe even yarn had issues. And we had a rather stupid error not generating the correct bash environment variables at all.
These issues would have to be identified and backported to 1.2.x and an all platform release compiled. And we will end up with component versions which are obsoleted by new stable versions.
On the other hand, for current trunk aarch64 is a first class citizen now : https://ci.bigtop.apache.org/job/Bigtop-trunk-packages/
(aside from ambari).
I'll advocate strongly to get 1.3.x finished, rather to fix already fixed issues.