Disagree.
https://jordanbean.medium.com/analyzing-mlb-attendance-and-temperature-6cb2b1af2bd4 The chart here (I think for 2007-2017) indicates that attendance is certainly higher in the summer, but nothing to sneeze at in April/May. April / May around 27,000 per game, June around 31,000. Both sides need all of these games.
Another important factor is that if a delay happens and a month or two are missed, a percentage of fans simply won't come back, to the TV or the ballpark. MLB has enough perception problems without causing this seismic one themselves. They can't be this stupid, can they?
Yesterday's meeting was under a 1/2 hour. Both sides exchanged counter-proposals, and they agreed to meet daily starting Monday.