Yeah I understand your objections. The problem I have with the "GM helps the player to do the tactics and fudges the monsters moves in order to give the player the advantage" is that it's kind of awful. For one thing, your tactics as GM may be no better than the player, and making the monsters behave poorly just to give the player the advantage for having picked tactics skill is not very elegant.
Yes, agreed that if the GM sucks at tactics he should go for a plain bonus if there is prep involved. Meaning the Player with the skill has at least 5 minutes or so to plan ahead.
But if the GM has at least a bit of knowledge it can be better to go the assistance approach. Why? so that a player that knows no tactics can think up stuff. Sometimes a proper tactic will help more than a bonus plus it adds to the feeling of the character. Lets take some examples:
Player is familiar with tactics, however he didnt buy the skill.
GM: "the enemy charges at you from the sides"
Player: "hmm they are flanking us, ok lets do this XXXXXXX"
Player is not familiar with tactics, however since he wants to play a war vet he buys the skill "Tactics" so he is able to perform at what his char should not tied by his own lack of knowledge:
GM: "the enemy charges at you from the sides"
Player: "ok sorry i dont have a clue what to do when flanked like this, can i roll tactics and you can tell me? i mean, my char should know even if i dont"
rolls tactics *success*
GM: "ok, you can try this XXX or YYY as the most usual ways to counter flanking"
Another way could be preemptive
Player: "ok i park here and decide to go inside"
GM: "ok roll tactics"
Player: "uh? what for?"
GM: "just roll it like if it was a Perception check, to see if you notice something, etc".
Player: "oh ok, here i go" *success*
GM: "you realize parking near the back exit would be a safer call than parking here on the street by the main entrance".
And none of this past examples means fudging the opposition, just give some advice to the player, still play opposition to the best of their ability. Granted it depends on the GM.
To start coming to some conclusions. Would say
1) if GM is not confident enough to advice, then go for a plain bonus to some rolls when they have time to prep. Strategy per se will have to come from the Player itself. GM has to inform the player that's how its going to go beforehand so to be careful not to grab something he doesnt know how to play.
2) if GM is confident, he assists with some tips. If the roll is, lets say, a critical success, the character might even guess a bit what the opposition is planning to do according to their movements/positioning.