While the Belgian government and post-war tracing services opted not to conclude on Emanuel's fate, it is possible to conclude in favor of one possibility over the others in Emanuel's situation.
The confusion regarding Emanuel (and his son, Joël)'s fate is due to the nature of their deportation. Mechelen Convoy VI departed on 29 August 1942 with both men onboard, as well as their wife and mother, Esther Pimontel-Dreesde.
This convoy stopped at Cosel, in Silesia, where men between the ages of 15-50 were ordered off the train. These men were later transferred to various labor camps in Silesia to work under Organization Schmelt. Most of these men arrived at Groß-Rosen initially and were eventually dispersed to various smaller labor camps in Silesia.
We know from survivor's testimonies that it was not uncommon for father's of young sons to lie about their own age at Cosel, as to not be separated from their sons; one survivor from Convoy VI, Nathan Ramet, reports that his father Judka, lied about his age so that he could depart at Cosel and remain with Nathan.
It is very likely that Emanuel Pimontel lied about his age to stay with his son, Joël; Emanuel was only 52 years-old, so very close to the age cut-off, and Joël was very young at 17.
It is always possible that Emanuel stayed on the train with his wife, Esther, but its likely Nazi officials would have forced Joël off the train and I believe it is likely that Emanuel followed. The Pimontels were registered at Mechelen with other Dutch diamond-working families from Amsterdam that they likely knew very well, and thus Emanuel could have felt comfortable leaving Esther in their care (and she may have encouraged Emanuel to stay with their son). None of the other Dutch diamond families had children on the transport, thus if Emanuel did not go with Joël, Joël would have had to leave the train alone.
I think it is most likely that Joël and Emanuel departed the train together at Cosel and were transferred to Groß-Rosen and perished there or at one of the other labor camps in Silesia. Many deportees from this transport ended up at Groß-Rosen, Babitz, or Klein Mangersdorf, where most were building the Reichsbahn as forced laborers. They likely perished at one of these Silesia labor camps in late 1942 or 1943.
On the less likely possibility that Emanuel and Joël remained on the train and arrived at Auschwitz, based on statistics for this transport, they likely did not pass selection and were murdered the same day in the gas chambers.