No, it wasn't. That was an ultimate sacrifice for desperately fighting Homeland.
The tour guide in Vizna told us that before the battle they solemnly swore to defend Homeland to the last drop of blood and to the last bullet and that nobody would be taken a POW from the battlefield with his hands up. The swore they would never surrender and THEY WON!!!
Heinz Guderian wrote in his diary that on that day he was defeated and humiliated as never before. He admitted that it was his army that was crushed. He wrote that if Poles had had only a half of German resources, his army would have been doomed within a day. Then he himself was walking on the battle field to see the faces of the killed Polish soldiers as he couldn't believe his army had been stopped by 800 Polish soldiers. It speaks for itself.
Making the ultimate sacrifice would have been making a final charge at the Germans. Killing yourself is pointless and a sin.