Here it is:
View attachment 145356
To me that seems pretty clear: as long as you have any exertion left (after paying the two points), you can make a melee weapon attack.
I’m not sure the order of operations makes sense that way.
The maneuver itself costs 2 exertion and a reaction, the first paragraph is fluff, the second paragraph describes what it does when you spend those 2 exertion and a reaction.
What you are proposing is that it takes 2 exertion and no action to activate the maneuver, and it then grants you the ability to use your reaction to do something in restricted circumstances. I‘m not familiar with the playtest or what might be included in the general rules for using maneuvers, but from just looking at this maneuver as written it seems like an awfully strained reading of the text.
That being said, there isn‘t any clearly good reading of the text! For example, itcould be interpreted that you use a reaction and 2 exertion to activate, and then you have to wait until you get your next reaction so you can use that second reaction to activate it. I actually think that‘s a slightly better interpretation of the text, but it‘s still not a very good one.
The one good interpretation of the text I can see is that there are some situations when some characters (maybe a special subclass, or a feat, etc) are able to use a 2 exertion maneuver despite having an empty exertion pool, and the fine tuning math determined that it wouldn‘t be balanced to allow with this maneuver.
If such a “free exertion” feature were at-will that would make perfect sense, because this maneuver would then be almost as good as just saying “you gain one extra melee weapon attack per round”.