All outdoor events are subject to a 500-spectator limit from Boxing Day for a period of up to three weeks, although there are fears that could be extended.
National clinical director Jason Leitch stated this week that public health officials and politicians "had to draw a line somewhere" and admitted it was very difficult to choose a number.
But Alexander, whose side host Livingston on Boxing Day, said: "I don't see the sense in just coming up for a number - 500 for us and 500 for Celtic is completely different. It might be the same number but it's completely different relevance for each club.
"I think things like that undermine other messages that are evidence-based and thought-out, and there's an idea behind a decision.
"Throwing a number because you have to draw a line, that for me weakens any other argument you come up with when you are making decisions.
"I think that's just decision-making on no evidence at all and no understanding of the contrasts between each club."
The cinch Premiership winter break was brought forward in the wake of restrictions with two sets of festive fixtures put back until mid-January and early February.
Alexander said: "It's a common-sense decision to bring the break forward. We are a little bit disappointed that we are playing Sunday - not the actual game but in front of only 500 fans.
"We have seen the contrast between no supporters and a full Fir Park. It's a massive difference for us.
"They are an important part of everything we do at the club, we are a fan-owned club, so to not have them here in numbers is disappointing, but we have to understand the scenario we are in at the moment.
"But I thought bringing the break forward was the only decision.
"We didn't want to play in front of just 500 but it's for one game, hopefully, and when we get back in January, fingers-crossed, the next three weeks will give people the evidence to have confidence to bring supporters back into stadiums and we continue to play football."
Motherwell have won their previous three games at Fir Park without conceding a goal.
"Hopefully the lack of supporters won't impact the atmosphere of the game too much because the supporters have been brilliant this season," Alexander said.
"We have to try and recreate that just with the players and the lucky 500."
Alexander will not do anything different in the dressing room before the game to try to compensate for the lack of atmosphere.
"I'm not that way inclined to be honest, about whipping players up to a frenzy before a game, I think the energy has to be spent during the game," he said.
"For me it's about focus and concentration before games to be honest, to actually focus on our jobs. But I know supporters and the atmosphere plays a part during games when things happen, both in a positive and negative sense.
"So it's more while the game is going on that supporters impact on a match scenario.
"I think all players will have had an experience of it but we have seen when supporters are in it's a big difference and it's a positive difference."