Not Meant for the Spotlight

Just returned from a rehearsal where it happened again.   I don't know what it is with conductors, if they get a kick-back from sopranos for bars sung or if they just can't bear to hear a melody line without the sopranos in it?  Tonight our little church choir was blissfully rehearsing some anthems for Sunday morning.  We sang through Don Besig,'s  I Will Serve the Lord All My Days where in bar 35 it states Alto only.   Now what does that mean to you?   It seems that our conductor used some creative interpretation of the phrase "alto only" because he turned to the 9 sopranos and said, "in bar 35 where it says alto only,  just join in."  Pardon me?  There were 11 Altos and let's see, the range in the 'alto only' section is from the A below middle C to the A above middle C - hardly in the soprano's bag of tricks.  But all 9 of them raised up their music and dutifully joined in.  Where is the respect for the composer's markings? 
Does the conductor think the Altos can't handle melody line?  Is he afraid they will spontaneously begin harmonizing with themselves?  Does he think the sopranos will get up and leave en mass, soprano noses in the air, if the altos get to sing a few notes without them?    It seems he just does not see that as much as altos are good at blending in and  hiding in the chord it does give us a little thrill to see the notation "alto only", it is like being allowed to be Prima Donna for a day.   He does not know that by saying, "sopranos join the altos" he is taking the spotlight from us.  I guess it is just going back to where it belongs.  Why upset the order of things?  The heroine is always soprano.  Turandot as a mezzo?  Could Pamina ever sing below middle C?  Don't make me laugh.
 I did notice that the Besig Anthem ends in a high A?  I wonder if the conductor would object if the Altos joined the sopranos for the last bar, just to help them out, you understand.