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I'll make it short since this is a rather off topic discussion and we've had it plenty of times before:
Adding side tech cost for Allies only is completely misleading. Allied infantry is meant to have side techs by design, they need it to be competitive. The cost of those side techs as well as unit timings have been balanced with Allied main tech (that's why the pure Allied main tech path is cheaper than Axis counterparts). When the side tech has to be bought matters for balancing, but not for the overall point.
So you have two choices for comparison between Allied and Axis squads: Either add side techs to the main tech cost. Or as you say, add it to the unit cost. But then split some arbitrary amount of Axis tech cost to weapon upgrade/nade unlock etc as well. Because this is part of what their teching benefit, but Axis does not have a choice while doing so.
So finally after all that back to 5 men Grens:
Factoring in the costs here is okay, because you get them regardless of teching or any other condition. They have been balanced towards the LMG alternative, not the timing of another unit.