Connect with MySQL table type times out when results don't start within 40 seconds

I've defined a Connect table as the mysql type with a srcdef that is a group by statement that takes about 2 minutes to start returning rows. Here is an abbreviated example:

CREATE TABLE `thingsGroupedByDay` (

  `ownerID` bigint(20) DEFAULT NULL,

  `createDate` date DEFAULT NULL,

  `count` decimal(23,0) DEFAULT NULL

) ENGINE=CONNECT DEFAULT CHARSET=utf8mb4 

CONNECTION='mysql://user:pass@my.host/my_schema' 

`TABLE_TYPE`=MYSQL `HUGE`=1 `SRCDEF`='

SELECT

  ownerID,

  DATE(createTimestamp) AS createDate,

  count(*) AS count

FROM things

GROUP BY

  ownerID,

  createDate

';

When I try selecting anything from the connect table, after 40 second in my client I get:

`MySQL said: Got timeout reading communication packets`

I've set the net_read_timeout system variable in my.cnf to 3600 with no effect. I've also set OS and my.cnf level TCP keepalive values.

Tables with srcdefs that take a long time to complete but start returning rows immediately work great.

I found in the source myconn.cpp file in the MYSQLC::Open function a line that appears to fix the connection read timeout to 20 seconds:

uint        cto = 10, nrt = 20;

...

mysql_options(m_DB, MYSQL_OPT_READ_TIMEOUT, &nrt);

(https://github.com/MariaDB/server/blob/22b645ef5292387871b12b26fd550eed6e57aa2d/storage/connect/myconn.cpp#L492)

Is this read timeout in the Connect mysql client what is causing this issue? Is there a reason it was hard coded to 20 seconds instead of, if I'm following the code, being allow to use the net_read_timeout system variable?