I suggest that you or somebody else who is interested in the issue simply tries to run current Drupal HEAD on such a hosting account and reports back.
FWIW, The default value for MySQL's Create_tmp_table_priv is 'N'.
I tried the following on two of my shared accounts. Both give me the create temporary table. mysql> create temporary table x(y int(1)); Query OK, 0 rows affected (0.04 sec) mysql> select * from x; Empty set (0.00 sec) mysql> insert into x values (1); Query OK, 1 row affected (0.00 sec) mysql> insert into x values (1); Query OK, 1 row affected (0.00 sec) mysql> insert into x values (1); Query OK, 1 row affected (0.00 sec) mysql> insert into x values (1); Query OK, 1 row affected (0.00 sec) mysql> select * from x; +------+ | y | +------+ | 1 | | 1 | | 1 | | 1 | +------+ 4 rows in set (0.00 sec) mysql> drop table x; It worked on both hosts without a problem. My concern would be performance, not availability. Then again, I say "my", since some may not have that privilige just like the LOCK TABLE issue that comes up every so often.